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Review:Rockhopper Audio M3 Headphone Amplifier

post #1 of 16
Thread Starter 
This is a review of the new M3 headphone amp by Rockhopper Audio.

I burned in the M3 with 8610 for 150 hours before serious listening.

Smoothness is a strength that Mosfets are known for. Tends toward the tubey without typical unbuffered opamp coldness. No spit or sizzle.

Clean, full and lush tending toward a bit(and I do mean a bit) of warmth.

Solid and deep. Grips like a Krell amp with tight control. No wooly, loose or tubby-ness here.

Focus and Soundstage
Clear focus with instruments and voice delineated clearly and coherently from top to bottom. Soundstage is another strength of this amp.

Macro dynamics are good. Punchy. Good low level micro dynamics

M3 vs. Cmoy(s)
I have a standard CMOY and an “Enhanced” CMOY with OPA 134 and audiophile caps, which sounds very clean. I like the CMOY as you really hear the sound of the opamp with a minimum of other circuitry between the output and your headphone jack. I just like the idea of a minimalist design via straight wire with gain and love the concept of components such as passive preamps. However, the proof is always in the listening and the little CMOY falls short of the M3 in giving music harmonic undertones and proper decay. Can sound cold when compared to the M3.

M3 vs. Pimeta
The Pimeta with an 8610 should be a step up from the CMOY and sounds a bit warmer. Mine did not have the attack and definition of the enhanced CMOY and it seemed to be step sideways and not an improvement. Ho hum.

M3 vs. Melos SHA-1
The SHA-1 was considered by many (including Corey Greenberg and Stereophile in the early 90’s) to be one of the best sounding headphone amps. They sold for around $1000 new and today fetch over $400 used and cost at least that much to refurb through “restoration” sites. This Melos was smooth in the midrange and treble with good midrange texture and air around the voice and instruments. Bass on the Melos is not as deep and tight as the M3. This is where the M3 was simply more coherent. Dynamics were better on the M3. I did not hear a big improvement in soundstage of this SHA-1 over the M3, quite and achievement for the M3 as this has been a Melos strength over the years. I did hear a nice 3D soundstage through the Melos preamp output compared to my Aragon preamp but I did not hear a similar improvement in this area over the M3 via headphones. I wonder what the M3 would sound like with properly designed preamp outputs using the input ground?

M3 vs. PPA
The test PPA had the 8610 with Intersil 5002 buffers. As you would expect, of all the headphones amps tested the PPA sounded closest to the M3. The M3 had a smoother top end with more sheen around cymbals, superb treble definition, yet without sounding bright. I have heard MOSFET “haze” on amps from some time ago and was pleasantly surprised that this was not a problem on the M3. The PPA had more of a clinical sound. In the bass the M3 seemed to slew a bit more quickly than this PPA and sounded less congested during complex music passages. Decay was better on the M3. By comparison the PPA truncated trailing notes to a small extent. As good as the PPA is, it still lacked the smoothness of the M3. Attack was a bit sharper on the PPA. Bass and dynamics were better on the M3.

I have been chasing various headphones (and headphone amps) for 25 years. I have not been real happy with any of them when compared to the soundstage of speakers, but the M3 with Senn 5XX/6XX has caught my attention and brought me back to enjoying headphone listening. This amp is coherent and flat sounding from top to bottom. I am reluctant to submit such a good review of a new component as I realize I may be caught up in the “new is better” syndrome. But I CAN hear “the room” and soundstage with the M3/Senn combo on well recorded SACD’s. There is no hint of any Sennheiser “veil” with this amp; transients are good.

I would prefer to distill my notes, listen to more music and see if I am as enthusiastic after 6 months. However, I would rate my confidence in this evaluation as good. I would agree that in terms of design, the M3 is an evolutionary improvement over the PPA. In terms of sound, it is an incremental and audible improvement. The M3 was designed without compromises for portable use and it shows in particularly in the area of dynamic range.

I am not a big believer in voodoo or witchcraft, but I did think the unit sounded better after the 150-hour burn in particularly in the treble. My M3 also seemed sensitive to interconnect capacitance with the higher capacitance cables rolling off the high end and reducing transient response.

A word about the value of this amp. It is slightly simpler to build than a comparable PPA and I have seen assembled prices that are less expensive making the M3 a deal for those on a budget.

Thanks to Morsel and Amb for a mature design and alpha/beta testing procedures that reminded me of the New Product Introduction Process from the days I worked at a mini computer manufacturer near Boston. Thanks to Stephen of Rockhopper Audio for a professional build and a great buying experience.

Test system hardware
JM Labs 820 Cobalt speakers
Cayin TA-30/Prima Luna Prologue One Integrated Tube amp
Aragon 2004 Mk2 amp
Aragon 24K SP preamp
Rotel 991 CD and HDCD player (love HDCD)
Sony 333ES SACD player
Technics DVD A10 DVD-A player
Monster 2.4 speaker cable
Home Depot HD 14 and 16 speaker cable (not bad, read Audio Cable Asylum)
Silver Audio 4.0 interconnects

Stax SRX/SRD-7
Koss ESP-950
Senn 497
Senn 580
Senn 650
Koss KSC 35
Koss Porta Pro
Koss Porta Pro 2
Grado 80
Grado 225
Sony mdr V6
Sony mdr 780
post #2 of 16
Thanks to Morsel and Amb for a mature design and alpha/beta testing procedures that reminded me of the New Product Introduction Process from the days I worked at a mini computer manufacturer near Boston.
I worked at a mini computer manufacturer near Boston. Agents of order, unite!
post #3 of 16
Thread Starter 


Hi Morsel,
I worked at Prime computer for many years. The other big mini companies around Boston were Data General and Digital Equip. Corp.

The brightest hardware designers(such as you and Amb) were like rock idols in these companies. I will refrain from making a tasteless joke about any groupies you may have had following you around....

Were you a DEC Exec?
post #4 of 16
Thanks for the great review, I have an M3 on order from Rockhopper to use at work and as a 2nd home amp.
post #5 of 16
I used to work for Stratus (a maker of big and expensive fault tolerant computers, used to be headquartered in Marlboro, MA and now in Maynard), but my department, the Unix development group, was in San Jose, CA. So, I guess the "near Boston" remark sort of applies to me as well...

Getting off topic here.
post #6 of 16
Thread Starter 


Hi Tkam,
I think you will love the M3 mosfet smoothness with the Grado's . It is as close as I have heard any solid state amp come to the sound of a tube headphone amp.

Stephen's work for me has been top notch along with the quality of his parts(both specified and un-specified). Besides that, he is a real pleasure to work with as he builds his business.

Please let us know what you think after you break in the M3.
post #7 of 16
Nice words, well written; thanks, tbonner1. Gave me a very good taste for the M3.

As for the off-topic work tangent, I work in IT, and have been at Stratus (94-96), and Wang (86-94). I have worked in the past with several "Primates" as they were called.

amb: I always joked when Stratus was porting HP/UX to their hardware, I said they should called it S/UX

Lotta good times back then....
post #8 of 16
Originally Posted by skullguise
amb: I always joked when Stratus was porting HP/UX to their hardware, I said they should called it S/UX
Yep, since the original Unix implementation on Stratus was called FTX, we also thought that F/UX would be appropriate too.
Those were good times indeed.
post #9 of 16
I just purchased a prebuilt M^3 from Rockhopper Audio. I can't wait to compare it to my Little Dot MKIII.

I am a tube man but I want to see if a SS amp can win my heart.
post #10 of 16
Bump - I just ordered mine from Rockhopper too. It should be a winner.
post #11 of 16
A very good review and one that brings me a step closer to my decision. Thanks!
post #12 of 16


Originally Posted by Vandal View Post
A very good review and one that brings me a step closer to my decision. Thanks!

... you might want to check his more current reviews further...

"Rockhopper M3
I liked doing business with Rockhopper, but when I last checked he has stopped building amps. I have heard versions of this amp that sounded different with different parts, more than other amps I have compared with different configurations. This amp had 8610 opamps that I preferred with the Senns and Elpac “wall wart”. The amp can be improved with better power supplies.

Not a lot of air or sparkle and somewhat recessed.

Rich and clean but prominent in the mix.

Solid and strong.

Lack of air hinders the presentation and depth.

Good with Elpac, better with improved power supply and audiophile caps.


1-Bada PH-12
2-Doge 6210
3-Corda Opera
4-Singlepower PPX3 6SN7
5-Yarland P-100
7-Presonus Central Station
8-Little Dot III+
9-G&W 2.6F
10-Feel/OK2000 HP-100A
11-Little Dot II+
12-Little Dot II
15-Travagans Red
16-Xtra X-1
17-Ming Da 66
18-Xiang Sheng 708B
19-Pioneer A-35R
21-Marantz 2230
22-Enhanced CMOY


post #13 of 16
hahaha, the Little Dot II over the M^3? It was a fantastic amp for the price, but come on .
post #14 of 16
I believe he didn't have sigma with his unit hence the low ranking.
post #15 of 16
Even then that's a really odd review. The not-Elpac power supply helps, but not THAT much.
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