Would adding a Dac improve the sound for my setup?

Well, my $300 DAC operates in the company of Gamut L5s [$15000 retail] CJ 350 [$10500] Audia line stage [$7000] and 2 REL subs [$6000] and holds its own quite well. Is it the best DAC available, of course not; but HIFICRITIC said that they had never tested an active component at this price level that could be used in high level systems like the V-DAC. With an external power supply it is even better. It is just too cheap for most ; it took a friend almost 2 years to convince himself to get one. He is very happy with it.

I'm reading this thread after checking your system page and it leaves me wondering if you have installed the room treatments you mentioned. From the system pics, I see a very lively room. If you haven't addressed the room, I would strongly recommend that as the first step toward improving your sound.

I agree with Timrhu. It's hard to tune a system if it's in a untreated room.

Not all rooms need to be "treated". I am in my fourth room in the same house, two have needed treament and two have not. That being said, I agree 100% that if a room does need treatment, there is no better return on investment. Having just bought 8 various types of Real Trap panels (in addition to what I already owned), I can attest that some of these products are better than others, but addressing the room is key.

That being said, I can also state with a high degree of confidence the inherant weakness in the OP's CDP (but also its strengths).

Ok then I'll give priority to room treatment. Unfortunately I can only treat the front wall behind the speakers, because this is in our master bedroom. My wife doesn't want to see too many things. I'll put a artistic panel behind each speaker and start from there.