In my opinion I would get a dac that has output level control done in the digital domain, and connect direct to your amp. As this will be the most transparent/dynamic sound you can get from source to amp.
It would be nice to get one that you can set the max volume level, some have two/three or four setting done inside that give you a choice of output level, 0-2v or 0-3v output and I've even seen some that do 0-8v
What this means is you set it for your system so you can use it's digital volume control at and above 75%, so you don't run the risk of "bit stripping" it's not bad but can lower resolution if below 75% of full, on some cdp or dacs
Cheers George