It's a viable option. But yes, it lacks XLR4 and its gain controls are internal. So switching between headphones with vastly different sensitivities means you have to open the chassis and mess with dip switches. Doesn't seem convenient as far as amps go. And yes, I have multiple headphones. I think I'm going to try the DAC3-B and HPA4 for a few weeks via Benchmark's audition program. But my short list is:
DAC3 + THX 789 / Aune S7 Pro / Cayin iHA-6
Qutest + THX 789 / Aune S7 Pro / Cayin iHA-6
Cayin iHA-6 + iDAC-6MK2
Matrix Element X
I would say if you’re looking for a $2600 price difference in regards to sound quality and you’re not interested in the difference of features between the 789 and the HPA4, save your money. Though the HPA4 measures better there are diminishing returns in cost to performance like most of high-end audio.
A/Bing the two the difference for me was slightly more imaging/soundstage, the attenuator, and the prospect of being able to drive almost all headphones to their maximum capabilities. Do I currently own the Susvara, HE5k, or the Utopias? Not yet, but I want something that will stand the test of time that I don’t need to upgrade for many years. I can’t even imagine where Benchmark would go from here and how they could improve from a sound perspective.
I also wanted a line amp when I eventually purchase speakers. 5-year warranty vs
1-year warranty (but you could just get that from an 887). Touch screen vs no touch screen. External SMPS vs built-in so only an grounded AC cable is needed (though the SMSL SP200 has that feature). Remote or no remote, etc.
I haven’t been to RMAF or any Canjam’s but from what I’ve seen the HPA4 is used at a lot of booths to test out headphones so I think that says something. I’m happy with it and immediately sold my AAA 789. If I wasn’t obsessed with chasing the best in the THX AAA technology category could I have lived with the 789? Most definitely. It just depends on what you need and what you care about.