Simon Lee's compact class A/B amp is voiced for 'soft power'. That's its designer's declared sonic mission. The resultant shift into minor warmth, transient mellowness, strong bass and wetter textures really suited Soundaware's more crystalline converters. Lower resolution than the CFA-1.2 also narrowed the difference between XLR and RCA which I'd previously noted on the ultra-revealing ribbon earspeakers. In the below context and after accounting for the XLR's higher voltage, I'd call out RCA as being slightly sweeter and bloomier, XLR as more precise, dry and dynamic. On balance, this shift was lateral not vertical. As it had in the pure transport scenario, the more affordable A1X should be the preferred choice for most. That's particularly so if the rest of a system tends to the already very enunciated and crisp to benefit from a bit of laissez-faire and textural generosity.
Extrapolating from our Denafrips Ares 2 review via triangulating Frederic's take against my Terninator/Terminator Plus experience, it's fair to state that team Soundaware's aesthetic differs from Mr. Zhao's. Where Denafrips go after a denser more organic flavor, that of the A1X/Pro is about subjective articulation and precision. In transistor terms, today's components reminded me of high-feedback bipolar, not zero-feedback Mosfet. How about phoning it in? Final's D8000 represent Audeze's original aesthetic. The 8000 are fulsome and chunky planars just with better top extension than our LCD-2. At ~45 on the dial—when you press the hard chassis buttons or those on the remote, a brief volume readout appears—I had the usual SPL with headroom to spare. Into this friendly load driven 6.3mm, both X and Pro were essentially equivalent. Again I didn't hear a sufficient lead for Pro to earn its higher keep. Alas…
… this took a serious U-turn once HifiMan's HE-1000 jacked into Pro's balanced port. The included XLR4 adapter cable saw my XLR4/twin-XLR3 adapter to accommodate my Forza Audio Works custom leash. At ~50 on the dial, these high-resolution planarmagnetics which like their more expensive Susvara mates sound more electrostatic had full lift-off. This now was a very different league. I'd hit upon why to go Pro: balanced headfi into upscale loads. Any true vertical change translates immediately. There's more resolution, soundstage scale, layering, dynamic range. Everything gets bigger, better and more 3D. That's the jump the A1Pro made to finally earn its 100% surcharge. Even though its innards don't look anywhere near twice as costly, the actual performance of the upgraded headphone circuit certainly begged to differ. This was serious turf and the A1Pro not at all outclassed by the posh thin-film phones. To put it plain, even after two decades on the beat to have grown a mossy green of jaded, I'd happily live with this one-box solution of A1Pro+HE-1000. Whatever Soundaware's design team did to the balanced outputs made a demonstrable difference to elevate this now $1'400 deck into the majors.
Conclusion. Sadly few shoppers will appreciate my focus on today's machines as being their proven SD card integration. Liberated from Wifi, Ethernet and computers thus all their fussy counter measures to combat digititus, it equals high-end digital transports for less. Here X matches Pro to win on price. As single-ended D/A converters, they're equal as well. One more reason to favor X.
If you must have XLR, Pro is the one. Its sonic lead particularly with the lesser resolution expected for price-matched gear will simply be slim. Pro will only profit you fully with its optional headfi module. It adds a 4mm true balanced output + 4mm-to-XLR4 cable. It converts Soundaware's A platform into a serious one-box hub for Final Sonorous X/D8000, Meze Empyrean and HifiMan HE-1000 caliber loads. For active desktop boxes too, A1X/Pro are perfect. Enter USB, exit coax digital or RCA analog. Sized right for the task, their card slots invite quick drag'n'drop playlists to offline local files for superior playback while USB 3.0/Ethernet stream off the cloud, Bluetooth off your smartphone. That I didn't test the latter is due to our household's Wifi allergy. The resultant microwave radiation gives us headaches.
On sonic flavor, today's kit won't land us in fat city. It's voiced more matter of fact. It's not specialized but deliberate multi-tasking gear styled 'n' featured to be fashionable. In that it succeeds very well. Those curious enough to get seriously unfashionable should investigate SD card playback. They'll be shocked by what an A1X can dispatch for pence on the pound. It's when midfi becomes suitably high-end. Unless you do balanced headfi, the lesser of today's twins is less only on cost. Hence X really does mark the $699 spot. Become sound aware. Have fun with their A1X!