Danny,
Nice review.
I heard about this dac over at AA, there are some guys that wrote good things about it on the digital board.
Guys,
on the battery issues, based on what I know about batteries and some stuff I read on this dac at AA and their website.
They recommend 4 hours of listening between charge cycles, but that has to do with battery life. The more you discharge a SLA battery between charges, the less life it will have. So, you can listen for more the 4 hours at a time, but you would sacrifice some battery life if you do that. They said you should get at least 800 charge cycles, if you run it no more than 4 hours at a time.
Website says this for charge time:
<45min after four hours use (15-20min typical);
<2hr from deep discharge.
From what I saw, the dac automatically charges the battery when you turn it off. Sounded like you leave it plugged in all the time, and it is smart enough to start charging the battery when you turn off the dac. It also sounded like the battery was not easily replaceable, so as it comes from the factory, it is not set up for having a second battery to quickly replace the first one with. If this was really an issue, you could consider buying a higher capacity battery, if it would fit.
I also noticed they use parts that appear to be close to what Scott Nixon uses, the ACK DAC uses a TDA1545T and CS8414 where Scott uses a TDA1543 and CS8412.
The TDA’s are both inexpensive Philips DAC’s, the 1543 uses a I2S input. I would think they would be pretty close, if not the same, performance wise. The CS guys are digital receivers, the CS8414 goes up to 96Khz, where the 8412 runs at 44 Khz.
My last comment is on the battery power vs power conditioning “controversy”. My take on it is if an AC powered DAC needs power conditioning to make it sound as good as the ACK DAC (and at this point it is only a theory that it would sound as good), then that becomes part of the equation. On one hand, you have a battery powered ACK DAC, and on the other hand you have a different DAC and power conditioner. You have to weigh the advantages/costs of each solution, and decide which works best for you.
My really last comment is this also comes in a kit, which I like. Website said it was not simple to build, but seems like a competent DIYer should be able to handle it. Does not sound like you want to make this your first project though.
Randy