Can I connect DAC directly to amp?

you can connect directly, but there are some issues:

1) if you are not careful, you could blow tweeters or speakers if the digital volume is at max.

2) digital volume, even the best ones impact sound quality if you use too much. -10 dB is a good stopping point. If you are using only digital volume, you will need at least -20 dB.

IME, you are much better off to get a decent transformer passive linestage and use this for volume control rather than an active preamp or only digital volume. Here are some good candidates:

http://www.audiocircle.com/index.php?topic=89744.0

If you read all of the posts in the link, you will see that there are other interesting benefits of the TVC that apply to ANY system.

Steve N.
Empirical Audio

Edorr gave a good suggestion, that is if you use Jriver. As I understand it, Jriver (ver. 17 and above) processes digital at 64 bit so if you select the Internal Volume option you can reduce volume as much as you want without any impact on the 24 or 16 bit audio signal. I am currently using this option and so far it beats my passive and tube pre.

This thread gave me the idea of trying to connect my computer/DAC directly to my power amp and use the volume control in Amarra. It worked and sounded great. I don't see why doing volume control in the digital domain should degrade sound if it's done at a high enough bit depth. It kind of made me nervous though, and I won't be doing it on a regular basis, as one slip of the volume control or an accidental reset to maximum and it could be all over for the speakers.

get a good passive with steps for volume volumes on DAC are not that good.

http://www.goldpt.com/sa2.html

a good passive is a transformer-based passive, not resistors.

Steve N.
Empirical Audio