Originally Posted by dsavitsk
I would go 2 channel as, frankly, the third doesn't get you much but it does draw a bunch more current.
You know what, I honestly didn't even consider that. I envisioned it as some sort of BantamDAC + Mini^3 with a modified power supply, but since current is a bit tight, I can stand dropping a channel.
I'm going to need help figuring out how to do the current draw calculations. I really don't know where to start. Each chip is going to sink some sort of quiescent current as well as operating current, then there's the current going into the likely low-Z headphones. Preliminarily, let's try the AD8397 and see what kind of numbers we get.
If things work out with rds' power supply, we'll have 12V to work with. The datasheet says max current draw at a 10V supply is 12 mA/Amp (milliamps per Ampere? What does that mean?). The PCM2702 will take at max 30 mA for the digital section and 25 mA from the analog section. That means 67 mA so far, and rds gave us 150 mA of play. That means there's a healthy 83 mA to play with, yes? Plus, one of the features of the AD8397 is that it's capable of delivering 310 mA into a 16 ohm load. Should that worry me? What am I missing from my calculations?
Originally Posted by Mellow Mushroom
why not use battery power instead?
Part of it is because I don't want to have to worry about charging it all the time, and part of it is because it will be taking the signal from the BantamDAC. It would be some kind of headache trying to fit some sort of battery in there, figuring some sort of charging method, blah blah etc. I'd rather just have one wire in and one wire out, one for the DAC, and one for the headphones. It's simpler and cleaner that way, I think.