Ok,
I have tried 3 different headphone amps, various interconnects, a new Onkyo DX-7555 Audiophile Grade CD player, and have extensively burned in all of my headphones, amps, interconnects, the Cardas and Equinox Sennheiser replacement cables and have come to some new conclusions:
For overall BALANCE, detail, smoothness, and timbre, using the STOCK cables on all the headphones, and averaging the sound of all of my CD players, amps, and interconnects together, here are my preferences in order [1 - best, 6 worst]:
1.Sennheiser HD-600
2.Beyerdynamic DT-880
3.AKG K701
4.Sennheiser HD-650
5.Beyerdynamic DT990
6.Grado SR-60
Using the Sennheiser Equinox replacement cables for the 600 and 650, here are my preferences:
1. Sennheiser HD650 [using Headroom Max amp and Onkyo CD player]
2. Sennheiser HD600
3. Beyerdynamic DT880
4. AKG K701
5. Beyerdynamic DT990
6. Grado SR-60
Headphones using all options [1- very poor, 5- average, 10 - exceptional]:
Bass [combination of power, extension, detail, and quality]:
650:9.5
600:8.5
880:8
990:8
AKG K701:7.5
SR-60:7
Midrange [smoothness, neutrality, detail, openness]:
650: 9.5
600: 9
880: 9
701: 8
SR-60 :7.5
990: 7
Treble [extension, openness, smoothness, neurality, detail]:
650: 8.5
600: 8.5
880: 9.5
990: 8.5
701: 8
SR-60 : 7
Soundstaging:
650: 9.5
600: 8.5
880: 8.5
701: 9.5
990: 8
SR-60: 6.5
Strengths:
650's with Equinox, Headroom Max amp, Onkyo DX-7555 CD player: Simply outstanding in my opinion! I never dreamed the 650's could ever sound anywhere near this good!
I went from wanting to sell these to never wanting to let them go!
Exceptionally balanced, smooth, full bodied, excellent timbre, NO SIBILANCE, WIDE spacious soundstage, remarkable detail, and openness, with no harshness, organic, natural, extremely refined, incredible bass and mids,detailed and open top-end. Wow! I feel that there is probably no limit to how good these cans could sound with the proper amps, sources, and cables!
My new reference by a good margin!
So far best sound amp wise, has been with the Headroom Max. IMHO, it sounds better than the Creek, Heed, and the MF X-Cans v3 that I used to own.
But... with the STOCK cables and using the Creek or Heed amps, several of the other phones surpass them, and they sound muddy, too laid back, slow, bass heavy, and rolled off on top.
600's: When using the Equinox cable and Headroom amp, the 600's almost equal the 650's, but not quite! The 600's still have a very small tad of grain, and a slight thinness to their sound, but they still sound exceptionally balanced, smooth, detailed, and have great bass and top-end.
In their stock form, I feel that they are the best balanced of the bunch.
880's: Remarkably neutral, except for a emphasis in the top-end, and a very slight thinness to vocals. I feel that they have more bass quantity than the 701's.These are extremely detailed cans, especially on top, very neutral midrange, and bass range, great soundstage. I really enjoy these cans.
701's: I have a love/hate relationship with these!
Some days I like 'em, some days I hate 'em.
They are remarkably detailed, revealing, and have a great soundstage, but...
to MY ears they sound a little TOO detailed and alittle peaky in the upper mids/lower treble. They can be very hard on my ears, sonically, and with some music I have they are very harsh! Sometimes they sound much more harsh and grating than the Beyerdynamic DT880/990. Its not burn-in either.
They have about 600 hours on them. And this is using a wide variety of amps and sources. They do sound very balanced form the mid bass up to the middle midrange, and in the top-end. But there is that annoying little peak in the uppermids/lower treble that keeps rearing its ugly head at me!
990's: These are ok, but they do not really suit me tastes. They do have some really strong points such as dynamics, punch, and energy, but at they same time I feel that they are slightly too boomy in the bass, recessed in the mids, and alittle overemphasized in the highs.
Grado SR-60: Sound really good for the price, but they also sound ENTRY LEVEL in my opinion, compared to the other ones.
Good bass power and punch, but a tad boomy and lacking in low bass extension. Really good midrange qualities, and a very detailed slightly forward midrange, good highs, but they lack ultimate extension and air. For the price though: Exceptional!
Best sound Amp wise:
650 - Headroom Max
600 - X-Can v3 or Headroom
880 - Creek
990 - Headroom Max
701 - Heed
SR-60 - Creek
Still waiting on my HeadAmp GS-1!
Amp wise:
Top end extension: Creek
Treble detail: Heed/Creek
Lack of grain, harshness: Headroom
Midrange detail: Headroom
Bass power, punch, detail: Headroom
Blackness between notes: Headroom
Soundstaging: Headroom, sometimes Heed.
Amp build quality:
1. Headroom Max...remarkable!
2. Musical Fidelity X-Cans v3
3. Heed CanAmp
4. Creek OBH-11
Comfort:
1. Beyerdynamic DT880/990 [tie]...simply the most comfortable!
2. Sennheiser HD600/650 [tie]
3. AKG K701
4. Grado SR-60
Enjoy!
