im glad more people are realising now. I have NOT had a solid state DAC as my main source component ever since I heard a circa 1999 Audio Note DAC 2. My current SW1X DAC is obviously much better but that was my first experience with a NOS tube based DAC. It was a massive eye opener for me. I absolutely agree about your listening fatigue comment with other DACs. I even get it with the highly regarded DCS gear. 

 

Having used it for about a month now (for around 150 hours – 175 hours). Have jotted down few thoughts below on my experience so far…

My current system :

SONIC TRANSPORTER i7 Music Server > EtherRegen (Uptone JS2 PSU + Mutec REF 10) > Sonore ultraRendu  (Farad PSU ) > Singxer SU1 with SOtM sCLK-EX Upgrade (Final Touch Audio USB + Paul Hynes PSU + Mutec REF 10) > SW1X DAC III Special (Final Touch Audio AES)

Wilson Audio Sophia MK III speakers
Ming Da MC 300 PRE pre-amplifier
PS Audio BHK Signature 250 stereo power amplifier
Sunfire XTEQ12 subwoofer - pair

My Dac III Special has the following upgrades:
•   2 x Audio Note Copper Foil, Mylar in Oil signal output decoupling capacitors
•   4 x Black Gate de-coupling capacitors for TDA1541
•   Premium Tung Sol Black Plate 5676 tube form the 60s
•   Additional choke filter for the TDA1541 DEM power supply
•   2 x Audio Note 2W copper, non-magnetic, tantalum film resistors on plates of the output tube
•   Super HiB Double C core mains transformer
•   Super HiB double C core choke

I was previously using a Holo Audio Spring Level 2 Dac, so all my comparisons are with that as a baseline. Of course, it isn’t fair to compare a $ 1,800 Dac with an $ 8,000+ Dac but I don’t have anything else to compare it with. So with that in mind.. my brief subjective notes on the sound are as follows :

•   Better soundstage depth, width, and height, more Holographic / 3D
•   Music has more weight & impact across the frequency spectrum (more meat to the bones)
•   Improved lower bass & mid-bass impact
•   I am very treble sensitive. The Dac III has an extended, clear treble that doesn’t tip over into sibilant territory. Sound is non-aggressive to the ears, I
        used to get listening fatigue after a couple of hours on quite a number of albums before but can listen longer now.
•   Even albums that sounded ordinary before now sound good
•   Vocals feel more real, firmly placed center stage.
•   Music sounds more enjoyable., engages me more emotionally.
•   All the above are much more apparent on my Headphone system as compared to my speakers (for example. If sound improved by …say...20% on
        Speakers, on headphones it improved by 30% (the percentages are just for example))
•   In one of the SW1X DAC reviews someone else had mentioned this comment - “ I find it necessary to adjust the volume much more frequently than in the past. I believe this is due to more dynamic range though I am hard-pressed to explain the phenomenon”. My experience is similar. I now understand what the term “dynamic range” means.

The DAC shipped with a GE 5R4 rectifier (see footnote) but Dr.Slawa gave me a list of types of rectifiers I can experiment with. After about 2 weeks of burning in, I upgraded the rectifier to KR Audio 274B - HP (white base) & the EL86 tubes to NOS Telefunken tubes. The Rectifier swap added further improvements to soundstage width, depth & layering. The EL86 swap added more resolution, especially with the treble. All my comments/observations above were made after 4 weeks of using the Dac.

Some pics of my system & Dac internals :

Dr. Slawa was extremely patient through the whole purchase & build process and answered my numerous questions diligently. I was quite apprehensive about moving from a Dac on which I was upsampling everything to DSD512 , to a DAC which uses an old dac chip that only does 24/96 max.

Bottom line, quite happy with my Dac purchase.

Read the full review and discussion here

Please note that the product specifications may have changed since the original publication