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Enjoyed reading your descriptions of what Vinnie's "Pro" DAC brings to the equation over what his NOS DAC solutions already do. For those of you who may be interested here's another comparison -- this time a NOS-chip Isabella/Isabellina against someone else's "pro" version. The Isabella/Isabellina still has a sealed lead-acid battery. And pitted against it is the latest, greatest DAC from the likes of PS Audio, actually an original PerfectWave DAC, owned by me for nearly 3 years now and just recently upgraded to new Mark II specs (http://www.psaudio.com/products/audio/media-players/pwd-mki-to-mkii/). That upgrade brings many new features, among them "192kHz 24-bit asynchronous USB, NativeX mode (via a digital "Lens"), non-saturated logic data path, 11 additional power supplies, lower jitter, and a precision balance control for the volume".I might mention that 3 years ago when I was in the market for my first external DAC, I had narrowed things down to the PS Audio unit (which was just about to debut then for "beta" testers only) and the Isabellina DAC option that Vinnie could provide in his Isabella. The primary appeal of the former was some very attractive promotional pricing as one of those testers, along with an accessory board promised down the line (the so-called “Bridge”), meant to enable the DAC to process audio stored on a network server. The appeal of the latter was Vinnie's power-supply solution, a tube-stage preamp, and option for headphones, all wrapped into one (along with Vinnie's exemplary reputation for quality and service). Some might say I was looking at apples and oranges. But the 30-day trial periods with both that soon followed attested differently in at least two essential respects.To make a longer story short, after mostly a month of very exacting side-by-side comparisons, I decided to keep both. With playback of Redbook CDs from PS Audio's partner PerfectWave Transport, the two DACs were virtually indistinguishable from one another in both sound character and quality, although I gave an ever-so-slight edge to the Isabellina. My reason for keeping the PS Audio unit boiled-down, essentially, to a new and successful justification (on my part) for a second DAC, the nearly exact similarity in sound and performance (PerfectWave DAC vs. Isabellina), plus the promise of a networked-audio capability to follow.Now ratchet ahead about two-and-a-half years. I still had and was using both units daily. The Isabella/Isabellina was/is still original, still featuring JJ Electronics vacuum tubes, and still not upgraded to Vinnie's LFP-V solution. The PS Audio unit was still original, too (except for a couple of firmware upgrades), and still without networked audio, although PS Audio had debuted their Bridge for that purpose about 1 1/2 years earlier. Frankly, "perfection" on that front still eludes the company and remains months-and-months away from a resolution that could persuade me to finally buy-in and implement what they intend for music over a network. Even so, come last November when PS Audio announced an upgrade for their DAC, (independent of any intention to improve their implementation of networked audio with the unit), then later when rave reviews began trickling in from early adopters, I decided to reserve one for myself and at least give it a try. The upgrade is nothing more than a (albeit expensive) replacement circuit board. When the board finally arrived a few weeks ago, I was quick to install it and start listening anew. Although I know enough to be leery of relying upon impressions before any kind of burn-in, I couldn't help noticing refinements right-off-the-bat over the original. Then last week, after several hundred hours of playing, I finally pulled the old Isabella/Isabellina from my other system to do extensive side-by-side comparisons, also to use it as a stand-in for the old PerfectWave DAC (again, since the two tested to my ears as virtually identical a few years earlier).(Parenthetically, while my testing setup this time may cause some here to cringe, it nevertheless permitted quick-and-easy, microsecond switching between the two units via remote control. All signal and digital cabling was garden-variety. My source was a PerfectWave Transport playing Red Book CDs in native resolution, outputting to both the PerfectWave Mark II DAC (via proprietary I2S HDMI) and to the Isabella/Isabellina (via AES/EBU). According to everything that PS Audio has to say on the subject, I2S HDMI is the better-sounding connection between their transport and DAC, therefore of distinct advantage here in my listening setup to theirs over Vinnie's. The Isabella also doesn't feature a bypass-able preamp section, which further handicapped it during my audition since I connected it and the PWD to a preamp for remote-controlled switching of inputs. [Less objectionable, perhaps, is that that preamp was the passive and very, very good "TAP-X", by Bent Audio]).And the verdict of that run-off? While native playback of Redbook CD through the PerfectWave combo (via their preferred, proprietary, digital connection) has definitely improved with the Mark II upgrade, the digital-analog rendering by the Isabella/Isabellina (with the same transport but a less-desirable AES/ABU connection) still manages to come out on-top. My ears may tell me that it's just by hair -- that if I hadn't been able to do instantaneous switches between the units in my testing, I never would have heard a difference. Nevertheless, I find it astounding. With respect to the parameters I set in my testing -- and despite expediencies in my setup that stood to favor the rival device -- Vinnie's 3-year-old implementation of a NOS chip beats the latest/greatest from a venerable, better-known (and significantly larger and older) maker of higher-end audio gear. While it would be hyperbole here to claim victory of the likes of David over Goliath (actually, the PerfectWave Mark II DAC, with its higher resolution, asynchronous USB, very competent musical performance, plus network music upgradeability is probably the real "giant killer" here, as its fan boys on the PS Audio forum presently claim), credit should go where it is due, and in this Vinnie deserves far wider acclaim than he gets. I say, let's spread the word!And, Vinnie, I am glad you are still around, doing what you do!
You probably know this, but having experienced every level of upgrade offered by RWA for HPA / Sig 30/30.2, I have to say you must still look up to see the top of the mountain. Both NOS tubes and LFP batteries hold meaningful potential to improve what you hear. Not to dis the stock tube, but I could not listen to my system with the JJs. And LFPs will do more than you might imagine to speed, bass punch and other variables. LFPs have much lower resistance, a variable that makes a surprising difference.
Always good to read another accolade on the benefits of upgrading to LFP's. I intend to do so this summer after a move. Finally tried different tubes last year: some vintage, haloed Siemens that were supposed to be the cat's meow, at least according to a couple of reviewers, at least in their gear. Couldn't hear enough of an improvement, though, over the JJ's to justify what I paid for the Siemens. In retrospect, I may have just picked the wrong brand for the Isabella for a substantive change from what the JJ's deliver.
Several times I attempted to use JJs during breakin for a new RWA product or upgrade to an existing RWA component, and in all cases I did not make it to the 100 hour mark without slipping the 7308s back in. To my ears and in my system, the delta was substantial.
