Upgrading Nest Desk Audio ~ From Good To GR8: NAD & Woo Audio To Black Ice 25Aug24

In audiophilia there are always improvements to be made. My recent measurement of the NAD D3045 Class D amp/dac on my Nest Desk, driving the Blanda108NSs, prompted me to look for even better power. Don't get me wrong, the "salad bowls" sound great with the NAD ~ I bet they can sound even better though with some EL84 power. I bought the Black Ice Glass FX10H integrated amp. My Blanda FE108NSs are fairly efficient @ ~87dB (SPL 1m/w) and are well-matched to that amp on paper. Plus, it's cool looking. My current FX10H is a 12 w per channel (given 8Ωs with stock Psvane EL84s) class AB amplifier. It's entry level from Black Ice but well regarded... at heart I'm just a low-mid priced audiophile and now a DIY and tube guy. It's got a unbalanced headphone jack so has potentially wide use on the Nest Desk. In with the new, forever remember the old.

Black Ice FX10H and stock Psvane EL84s; it was all solidly packaged.

The first A-B testing was done in COS for headphone listing; I used the Schiit Gungnir MB DAC to feed both the FX10H amp and the Schiit Mjolnir 2 headphone amp. This is my reference headphone stack to drive the killer closed Mr Speakers planar magnetic cans. Wow, Black Ice delivered on the headphones out. I was concerned but 1st, it was dead quiet even when cranked and the material was paused. 2nd, fidelity on all the tracks I tried (AJ Lee, Sammy Rae, Molly Tuttle, Phoebe Bridgers) was basically the same on either amp to my ear. 3rd, the Black Ice sound is just a skosh warmer, which is fine. Howdy, the FX10H runs every bit as hot as the Schiit, and that's hot. Each could be cranked with depth and coherence beyond where I was comfortable. 4th, no fatigue using the Mr Speakers driven by either amp. I am very pleased and impressed with the Black Ice FX10H headphone support. If it can handle Mr Speakers cans well, and match the Mjolnir 2 in COS, it will have no issue with my Audeze set @ the Nest Desk. The next headphone test was to compare the FX10H to the Woo Audio WA7 Fireflies DAC/AMP ~ but frankly given the compare with the premium Schiit stack, Black Ice will win again. Yeah, I needed to true the tubes in the Black Ice ~ I did that after transport to Summit Co.

I took the glass top off in order to straighten the tubes. Scheme is easy and effective... I didn't even touch the glass to smudge it.

On the Nest Desk I really I need a DAC as well to take the bitstream from my Mac Studio on USB and send line level stereo analog to the FX10H... I used the venerable Woo Audio WA7 Fireflies to do this initially (there are DAC section line level out RCA terminals for this exact purpose).

I quickly confirmed what I expected... the Black Ice outperforms on headphone listening, not just as an speaker amp. I tried it with both my Audeze planar magnetic and my AKG dynamic cans. Again I did a direct A-B listening test with both amps still in place (it's a busy desktop right now to be sure). Immediately the cans sounded sweet like with my Fireflies driving them, but were more revealing at the mid-high area and had more punch in the low end. Again the FX10H is dead quiet, again its sound was big. This completes one acid test for a big changeover on the Nest Desk, the headphone amp... if I get an alternate DAC, I can sell the Woo Audio Fireflies.

Knowingly, the FX10H was designed with a subwoofer line out; I used this to drive my Blanda Sub of course. The new desktop sound from the Blanda 108NSs was fabulous across a range of content. Listening (I mostly used the recent albums profiled in August Music Appreciation, but some older favs too, especially Molly Tuttle) was great as the bowls emitted a substantially more revealed sound and broad sound stage than when driven with the NAD. Near-field listening is a challenging task for a driver and amp ~ one tends to hear it all very well, like with headphones. It must be very good to not be fatiguing. The FE108NS drivers are quite good for this task (they sound great despite the somewhat wonky SPL sweep data from Fostex) and the new amp brings more smooth, and more mid-high reveal, to the table in my setup. The low end also thumps much more strongly and I had to trim back and reintegrate the subwoofer with this amp. Strong female vocals and acoustic instruments were even more present in the mid-range mix and the high end (with less rolloff with them than with even my favorite FE108EΣ drivers), as with cymbals and tambourines, was great without harshness. I was even able to do direct A-B listening between the NAD and the Black Ice... and that is how I heard it. I am really pleased with the upgrade; it is time to sell the NAD D3045, good as it is ~ my foray into Class D amps has passed.

I measured the the Blanda Bowls driven by each amp. the 20-200Hz measurement is the sub alone while the other SPL curves are the NAD and Black Ice amp sweeps. The extra low end from the Black Ice is apparent... when summed to the sub it's raised up to my house curve ~ but I separated them here to focus on the main amps' differences. Too, the smoothness I reference for the FX10H is shown in the graphs of spectral energy; the NAD showed more and longer "hot spots" (orange& red) where aberrant energy is being delivered. The overall clarity of the drivers in producing sounds from 2Hz-10KHz with either amp is mostly equal. While the Black Ice does have a THD of 1.2% vs the NAD's .5%, that's not all that important for fun musicality IMO. The measurements are solid and support my listening conclusions. I could probably yet tame the humps at 2.5K and 7K with my miniDSP 2x4HD; I may yet do that at least as an experiment whether I leave it in the audio path or not.

Right now the kit is stunning and still counts on the WA7 ESS Sabre DAC.

To prep the Woo Audio WA7/WATP for sale I removed it from it's role even as a DAC. I installed my miniDSP 2x4HD in it's place. I'll have a decent 24bit/192KHz DAC and I'll be able to investigate smoothing the SPL response some using some EQ. As I listened some more I found the setup smoother overall and just as good as that with the WA7 DAC. I measured this new config completely flat first and found that performance is now even better than with the WA7 DAC! Very cool. Hmmm ~ I may yet have more to say.