Just received a set of speaker cables and 4 pin XLR to HE 6 cable from Steve Eddy (q-audio).
That's connected to the Hifiman HE speaker adapter box into a NAD M2, source is a Squeezebox touch via coax digital into the M2 (M2 is an integrated DAC/power amp, an interesting and unique concept, 250W into 8Ohm).
First impressions:
- Soundstage has better focus than with my Liquid Fire (#14, stock tubes, Berkley Audio Alpha DAC, Logitech Transporter). This is a big deal as the LF is struggling with keeping things in focus sometimes (I am driving the LF between 10am and 3pm range on the volume scale typically with the HE-6, using the top (high impedance) headphone out).
- HE-6 on the M2 has a very coherent sound, better than on the LF (bass, mids, high). Excellent for long time listening (as non fatiguing as the LCD 2 v2 on the LF, but better genre bandwidth). Not sure if eventually I'll start complaining about the sound being "too relaxed", I'll switch the speaker cables to SR Tesla Precision and see how much that impacts the chain.
- compared to the LF combo (and other headphone like HD800 on the LF), there is less "sparkle" with the HE-6 on the M2 (but this is after very few hours on the HE 6 and mere minutes on the q-audio cables, so I'll see if that changes later). I will play with the speaker impedance compensation on the M2 as that impacts this aspect of the overall sound. Again, flipside of "laid back, non fatiguing" is that you can't have showy-flashy at the same time ...
- definitely nothing "harsh" or bright going on, I am super sensitive to that, no complaints. At any volume, including low volume (the true challenge when connecting the HE-6 to speaker taps), the amp is driving the phones with great detail and ultra black background (most of the amp chain is in the digital domain and NAD put in some proprietary magic to even compensate for power line noise algorithmically before converting the signal to analog).
- the Hifiman HE adapter box is a must for this amp because it's class D (don't want to try and put the phones directly on the speaker out).
To come: I am upgrading a bunch of things on the LF rig, including switching interconnects to SR Apex RCAs and upgrading power cables all around (SR Hologram As and Ds).
I plan to report back findings in a while, expect 2 weeks of burn-in on the M2/HE-6 before I'll put the rigs next to each other and do some real critical listening.
Too bad i missed the Seattle meet (was on vacation), would love to bring this combo to the next one and compare vs. that RSA HE-6 amp and other favorites. While a good choice, I didn't feel that the Liquid Fire is the be all and end all for the HE-6 and so rather than buying another TOTL DAC plus a LF I gave the NAD M2 a chance, specifically for use with the HE-6. So far, looking promising but not yet sure if it will keep me away from Stax forever