Koss ESP/95X Headphones vs. Sennheiser 6XX From Drop; Electrostatic Ecstasy for your ears?
Koss ESP/95X Headphones vs. Sennheiser 6XX From Drop; Electrostatic Ecstasy for your ears?
Hey friends, good to see you again! If this your first time visiting, my name is Marcello. In this headphone review, I will be checking out the DROP KOSS ESP/95X HEADPHONE!
Founded in 1958, John Koss teamed up with engineer Martin Lange, Jr. to develop a portable stereo phonograph player with side-wing speakers. Their new product allowed listeners to hear music by plugging in the world’s first SP3 stereophone, and so it began! Koss has been developing and inventing headphones ever since. In 1990 Koss introduced the revolutionary ESP/950 electrostatic headphone. Drop, a community-inspired product designer and online retailer, decided they wanted to partner with Koss to revive the standard-setting sound of the ESP/950 for the Drop community.
Skipping out on the large battery pack, case, pleather earpads initially included with the KOSS EXP/950, Drop updated the color of the headphones to Drops exclusive midnight blue, swapped the pads for thicker foam pads in velour, kept the KOSS lifetime warranty, then dropped the price by over $500, giving birth to the Drop ESP/95X!
Electrostatic headphones work differently than more traditional headphones to create sound. Electrostatic drivers operate by placing a static electric charge on an ultralight film that floats between two perforated metal plates. Static cling and repulsion then cause the film to move when audio voltages are applied across the plates, which creates a distortion-free sound with little to no coloration.
For this review, I will be utilizing the included KOSS energizer and several digital-analog converters to draw my conclusions about the Drop ESP/95X sound and compare the sound signature to another Drop exclusive favorite, the Sennheiser 6XX! I will discuss my audio chain throughout the review, and I will list the gear used in the video description to check them out. As with all my audio reviews, I will provide the music playlist I used to evaluate the headphones so you can listen along. I am not being compensated for this review, and all thoughts and impressions are my own.
The review will cover five main areas. Build Quality and Comfort, Quality of Sound, including Bass, Mids., and Treble; Tonality; Imaging and Soundstage; and lastly Synergy and Comparisons. Then stick around to the end, giving my overall conclusions and comparisons to the Drop Sennheiser 6XX.
So, let’s jump right in! First off, I want to thank Sheldon for sending me his Drop ESP/95X to review! The support of great individuals and companies sending me products to review is a massive help to continue bringing you guys new content! So, let’s talk Build Quality, Specs, Comfort, and Design.
The Drop ESP/95X electrostatic headphone is an open-air design with minimal acoustic damping. The 95X uses a 1.5-micron C-grade polyester film as a diaphragm which has been coated with semiconductive material. The ESP/95X has a frequency response of 8hz-35khz and includes an extendable headband made from stainless steel, wrapped in a leatherette style vinyl, with a 12mm thick poly-ethylene foam padding. The yokes of the headband have horizontal and vertical pivoting with a lock and detach mechanism.
I recommend pulling out the stainless-steel extendable headband on both sides before attaching the headphones to the headband to make the process easier. Once on, the headband is very easy to adjust. The included ear pads are soft Velour-Wrapped foam. However, for this review, I will be evaluating the sound and comfort with after-market Dekoni pads Sheldon, the owner, upgraded them with. I will also link to the upgraded Dekoni pads at the end of the review.
The ESP/95X includes a proprietary 4ft cable with a 6ft extension cable. The Headphones are easily some of the most comfortable headphones I have ever worn. They are incredibly lightweight, weighing in around 353grams. The headphones feel similar to the Sennheiser 6XX, using a plastic-type material for their build. They don’t feel highly durable; however, this design also helps to keep them extremely lightweight.
One thing to point out, it’s essential to take great care to make sure the headphones are kept and stored in an environment that is free of dust and moisture, as Electrostatic headphones require more attention in this department compared to more traditional headphone technologies.
Included with the headphones is the required E90X Electrostatic Energizer, whose volume control has a dual concentric continuous audio taper potentiometer; WOOOOO say that five times fast! The double side volume control has a split shaft for balance. This is probably going to be one of the few areas of the energizer I don’t like. Using the volume control can be challenging to get the Left and Right audio channels to be correctly balanced. Koss does give you directions on how to do so in the included manual. However, I felt a better way around the volume control was to turn both sides of the volume control to the left.
Once both sides were wholly turned down, I then turned both sides together to the right with no music playing, and then I utilized the preamp of one of my DAC’s or another headphone amplifier to control the volume. I will talk about this a bit more in the sound and synergy section of the review. In addition to the volume control on the front of the energizer, you have a power-on rocker switch, headphone output connection, and a 3.5mm audio input. On the rear of the energizer, you have the power connection for the included AC power adapter and left and right RCA inputs.
The energizer feels a bit less built than I would prefer, with a plastic enclosure and a very lightweight feel. The energizer can also experience audible interference if it is placed near a source that has 60hz noise, such as a power amplifier or some high-intensity lamps.
The noise will present itself as a constant hum. Owners of tube amplifiers will already know these struggles, as some tube amplifiers and tubes, in general, are more susceptible to things like Wi-Fi interference from routers or other Wi-Fi devices.
I did experience this one time, in the several weeks, I was able to review the headphones. All I had to do was find a new place for the energizer on my desk, and I was good to go. So, don’t let that discourage you if you are interested in giving the system a shot.
I will link to Drop’s website in the video description so you can go into more depth about the energizer and headphones specs such as frequency response, THD, signal to noise ratio, and more if that’s your thing.
I hope you are enjoying this review so far! If you are, don’t forget to subscribe to our email list for more content, and share with a friend, I greatly appreciate your support!
Next, let’s get into the quality of sound! The ESP/95X produces a transparent, airy sound signature, with excellent detail reproduction from well-recorded music. So, let’s kick off the quality of sound first by discussing Bass. Bass on the ESP/95x to my ears sounds very weak for most modern genres of music. If you enjoy Bass from your headphones and don’t plan to use EQ or tone control to increase the bass frequencies, you may be disappointed. Modern music such as electronic, pop, and rock didn’t have enough for my personal music listening preferences.
When comparing to the HD6XX, which are not considered to be an extremely Bass-heavy sound signature, to my ears, the KOSS had even less bass presentation than the 6XX. Running the Koss through the preamplifiers of the Feliks Audio Elise and the ZMF Pendant seemed to help my perceived audible representation of a bit more additional warmth to the overall sound signature of the KOSS.
I took it a step further and tested the KOSS with the Schiit Loki. I made some modest improvements to the two bass frequencies, 20hz sub-bass, and 400hz mid-bass regions, the Loki effects. The Loki enriched the sound of YoYo Ma’s cello and the string instruments from the Jurassic Park Theme Song. Where the Loki, in my opinion, couldn’t do quite enough was with a song Like Blinding Lights from the Weekend. Sub-bass and mid-bass frequencies from this track could not be altered sufficiently to help the overall presentation when using the Schiit Loki while still allowing the overall sound signature of the headphones to sound balanced.
I think EQ would allow for more control of more frequency ranges, and you could likely key in a much better-sounding presentation. However, for orchestral, classical, and some acoustic tracks with mostly vocals, the slight bumps from the Schiit Loki in the sub-bass and mid-bass regions were just what the headphone needed for my ears, to warm things up a bit and give string instruments and vocals a bit more weight and life. The midrange sounds decent to my ears. Again, in my opinion, I felt it benefited from some adjustment for much of the music I listen to. At times vocals could sound a bit nasally from certain singers. I found myself adjusting the 2kHz region down a bit on the Loki to allow for a more pleasing sound from vocals across much of the tracks from my music playlist.
The treble on the ESP/95X has intense clarity and image definition, more than enough from the presence and brilliance regions. I didn’t find the treble overly fatiguing from the KOSS ESP/95X. I was usually able to utilize the Loki to bring down the 8khz region if I felt there was too much brilliance for a particular track. The tonality of the KOSS ESP/95X is pretty good when listening to Orchestral and Classical music. Still, it doesn’t sound as enjoyable to my ears as the Drop Sennheiser 6XX, which I will discuss more in a moment when we get to that comparison.
So, let’s talk about the Stage and imaging of the KOSS ESP/95X. The stage of the KOSS is very airy and open sounding. This is one of the greatest strengths of electrostatic technology, in my opinion. Images on the stage are placed and defined exceptionally well, even competing with headphones three times their price, in my opinion. The stage size sounds decently wide left to right, not massive, but broader than the 6XX. When adding the ZMF pendant into the chain, the subtle tube harmonics allowed me to hear a slight bump in the overall size of the stage. The forward depth of the stage isn’t very deep, again a bit deeper than the 6XX. The biggest strengths of the 95X’s stage, in my opinion, are the amount of air and space they place between every instrument. Every sound and every vocal is so clearly defined, imaging exceptionally well on their stage.
So, let’s talk about synergy quickly before I compare it with the 6XX and overall conclusion. Since the KOSS energizer must power the headphones, I couldn’t traditionally roll amps as I would with other headphones I review. Instead, I decided to roll preamps and DACs with the energizer to give you my thoughts around them. The preamps I rolled with the energizer were the preamps of the Topping A90 headphone amplifier, the Matrix Element X, the Schiit Lyr 3, the Feliks Audio Elise, and lastly, the preamp of the ZMF Pendant. The Digital Analog Converters I rolled with the energizer was the Topping D90, Schiit Bifrost 2, and the Matrix Element X. With the KOSS Electrostats having such a clean neutral presentation as it is, I found the Topping A90 preamp, and the Matrix Element X preamp was my least favorite pairings with the KOSS energizer. The Schiit Lyr 3 was an improvement in the sound, in my opinion, as was the preamp from the Feliks Elise, as was the preamp from the ZMF Pendant. When trying to synergize an already neutral-sounding headphone, I felt adding any of the tube amplifiers into the audio chain was a step in the right direction. Which preamp you would prefer will significantly depend on the type of sound signature you are after.
As far as DAC’s, I preferred the Schiit Bifrost, first for its staging, touch of warmth, and to my ears, most natural presentation. Followed next by the Topping D90 and Matrix Element X. Both DACS have strengths over each other, in my opinion. The Topping D90 sounded a bit more immediate, punchy, and dynamic to my ears, and the Matrix Element X displayed a bit more relaxed in the treble presentation while still giving me all the details and a better stage presence than the D90.
I will leave links at the end of the review for all the products I am discussing. If you are thinking of making a purchase, please consider using one of my affiliate links, as I earn a small commission when you do. This small commission allows me to keep dedicating time and resources to bringing you more content!
So, let’s get into a quick comparison with the Drop Sennheiser 6XX! Remember when I am making comparisons or giving you sound impressions; they are always my subjective impressions. We may hear things a bit differently or have different audio chains that give us different impressions. That’s all good! With that said, to my ears, the 6XX is a much warmer sounding headphone when comparing them to the KOSS ESP/95X. The Sennheiser 6XX has the better overall bass presentation to my ears, even if it may be a bit less defined for some tracks. The 6XX is also the more dynamic sounding of the two headphones, with bass hits and drums carrying more audible weight and impact to my ears.
The 6XX has a beautiful sounding midrange that plays so well with vocals to my ears, which in my opinion, the KOSS ESP/95X will need some tone control or EQ to get the midrange to sound as good as the midrange of the Sennheiser. When comparing treble, the Sennheiser 6XX sounds a little rolled off, which may suit some listeners' preferences. The KOSS ESP/95X has a much airier and more shimmery top end, with excellent image definition and sparkle that the 6XX doesn’t present.
The timbre of the 6XX sounds more natural to my ears, with instruments and vocals just sounding more enjoyable to me overall. This again is my preference and will come down to your personal preferences. The stage of the 6XX is very intimate, with decent imaging and image definition. The KOSS presents a more open and airy sounding stage. The ESP/95X has precise imaging and a clear image definition, vastly superior to Drop 6XX. The Sennheiser 6XX will scale up and sound better across the board with a high-performing tube amplifier. However, the KOSS ESP/95X to my ears still has the superior sound stage.
As far as comfort between the headphones, I prefer the comfort of the Koss ESP/95X. They are so lightweight with very little clamp force compared to the tighter, less comfortable clamp force of the Sennheiser 6XX. When comparing the build quality of the two headphones, the 6XX feels more durable. They both have a similar plastic build, but I expect the 6XX could take a bit more wear and tear than the ESP/95X.
So, which one should you choose? Well, that is entirely up to you, and it will significantly depend on your listening preferences. I always recommend demoing a pair, as only you will know what sounds the best for you. The KOSS ESP/95X and the Sennheiser 6XX tend to go on sale from time to time, especially the ESP/95X. So, it’s worth creating a free DROP Membership. This way, you can keep an eye on their prices for any significant sales.
In conclusion, the KOSS ESP/95X are transparent, open-sounding headphones with image definition and accuracy on their sound stage, which is superior to more expensive headphones than they are. They have excellent resolution, with lots of sparkle in the treble region, and are highly comfortable to wear. Add to this the KOSS’s lifetime warranty and, at the time of this video, DROP’s 30-day return policy. This headphone system may be a good value for you if you place value on the benefits this system offers.
Suppose you are an audio enthusiast that is Electrostatic curious and enjoys classical and orchestral music and wants a different sound signature than something you may already own. In that case, the KOSS ESP/95X could be a headphone system you want to give a listen to! Don’t forget to subscribe to the YouTube channel and show your support using my affiliate links in the description below. Thanks again friends, leave me a comment with your thoughts on the KOSS ESP/95X and any other audio gear you want me to review next. Until next time friends, MUCH LOVE!
90 day free trial to AMAZON MUSIC HD
All impressions are my own, and we all hear differently, and that’s totally cool! I have listed some audio gear I use or recommend with affiliate links if I am affiliated with the company that sells them so you can check out some of the gear discussed and viewed In the video. If you have any questions or comments, please leave me a comment in the video comment section. I will always do my best to respond to each comment! If you enjoyed this video, please consider giving it a like and subscribing today. Don't forget to click the bell Icon to get updates when I upload another video! Stay tuned for more headphones, headphone amp, and audio gear reviews! Do you have an audio product you would like me to review for your company? Would you like to sponsor future videos and advertise your products, brand, or service to our channel viewers? Please feel free to drop me a message at marcello@mrhifireviews.com to discuss! Some of the links above are affiliate links. Every time you use one of my links as an Apos Audio/Headphonescom/DROP/Adorama affiliate, I earn a small commission which helps to support my family, me, and a large amount of hard drive space and filming/editing time needed for the channel so I can continue to bring you more video content! Using one of my links doesn't cost you anything more; it shows your channel support. Thank you again for your support. Much LOVE, friends! Marcello.
Music Playlists to test gear with:
