Okay, now I have measured my two amps driving HE-6: Burson Soloist compared to Audio-gd Master-6.
The Master-6 delivers 7 Watts while the Soloist is only about 1.4 W (in 50 Ohms). As far as I remember Burson spec'd the Soloist to 4 Watts in 16 Ohms, but has now changed it into 8 Ohms, which means it is rated half the original stated power.
EDIT: However, as Solude points out below, InnerFidelity has measured it to 2.2W in 32 Ohms, which translates into 1.4 W in 50 Ohms.
I measured both the Soloist and Master-6 at 50Hz, 500Hz and 10kHz to see how the balance was between the two amps and at two different SPL's: one at about 70dB and one at 101dB. Sine waves was sent through my SB Touch via S/PDIF to Audio-gd Ref 7.1 and then RCA to Soloist and XLR to Master-6. HE-6 was driven balanced via Master-6 and SE via Soloist.
I found two surprising things here:
1) There is no difference between the two amps in terms of balance at 70dB
and at 101dB. Well, this was no surprise to me, since I have heard this, but to others I expect. This means that in terms of bass and treble amount compared to the mids, it is exactly the same with either amp at moderate as well as very high constant levels. Actually the Soloist has 0.1-0.2 dBs relatively more bass than the Master-6 at both levels.
2) At 70dB there is relatively more treble than at 101dB, and that by a considerable number. This goes for both amplifiers (exactly the same difference). This suggests that
at higher levels (101dB) you have about 5-6dB less treble (at 10kHz)
compared to the mids (500Hz).
- Disclaimer: This relative decrease in treble could be caused by resonances or something, but I didn't hear anything.
If these measurements are true, it suggests that if you listen at safe or low levels, the HE-6 will sound brighter than if you turn up the level significantly. This of course is in addition to the loudness curve. (http://en.wikipedia.org/wiki/Equal-loudness_contour)
The following quote is from the Headfonia review and made me interested enough to buy the Soloist:
(However, I didn't think of it as my primary amp for HE-6, but for my LCD-2.)
Quote:
The Soloist definitely had what it take to drive the HE-6. Not only does the amplifier’s rated 4 Watts output sufficient for the HE-6, it also had a better synergy than my $3,500 RSA Dark Star amplifier. You all know how I am always for full bass and midrange body, and the Soloist comes with that sort of coloration. Driving the HE-6, it colors the HE-6 to be more Sennheiser HD650-like, boosting the low end body of the HE-6 to very musical levels. On the other hand the Dark Star gives a more spacious soundstage, but it doesn’t add body to the bass and mids the way the Soloist did.
To me, the Soloist is a super amp with HE-6. It doesn't have the headroom or power to drive it to very loud levels, but I want to keep my hearing and don't turn up the volume to more than about 80-90dB, at which SPL it still sounds awesome. I have chosen to mod my HE-6 with felt (decreases the treble) instead of turning up the volume to unhealthy levels ...
