You would get a different flavor from the system with a newer DAC. Either you would like it or not. It could bring more detail but maybe the more bloated bass from a cheaper DAC or the smoothness in general could be more pleasant for not trained ears.
I now use a Bottlehead Crack + HD600 + iBasso D12 DAC. It's a wonderful combo but after 8 months I feel I need more! The bass does not satisfy me any more now, I feel it shallow and everything else smoother than I would like it. As you I don't have a better system to compare with, nor headphones nor do I know someone that could let me test something better. I wan't something with tighter and cleaner bass, with more authority, also I wan't to attack a little the smoothness from the overall system, something a little sharper maybe, I would say datailed.
Either I could live with it as it is or I could start testing something else. The best bet for me would be to try other headphones, maybe Audeze LCD-2. But now I'm not willing to spend on other amp as well. I also thought on recabling the HD600 but I sincerely think I won't feel any dfference. I rolled tubes on the Crack and it do improved a little but I get used to it so fast that I don't feel the difference.
After reading a lot now I do realize that the right path would be to upgrade the DAC, and to make it worthwile it should be a DAC that can handle bigger sample rates and bits than redbook music, that means that the source also would play a big roll. Even the jitter that could live between the source and the DAC could be the bigger difference to notice a real improvement from a DAC, so improving the DAC as well as the source while taking care of the setup between the 2 would be the best by now until I decide to upgrade the headphones. Then I would also go for new cables for the HD600 and for the DAC between the Amp. I feel that after having take care about the DAC and the source, better cables would let me hear exactly the improvements that could bring the DAC and a better source, but not that some cables are going to really improve the music if the source is still cheap.
The thing for you is, get another DAC or not? I think that maybe by now you are fine, as I was. Later on if you feel the need, then you won't need just another DAC, but more discipline on how to use it and how to pair it with the source ;) That also means money and a lot of priority and love for your music and your newer hobby.
You can start at any point sincerely, you can start right ahead with a Bifrost or even a better DAC. I was about to spend on a W4S DAC-2. Nevertheless the truth is that I will be wasting it without better headphones, that DAC is already good for some decent speakers and amp, not just for headphones.
... Oh by the way! I just put my order for a Bifrost. I can bet it would pair well with the system. As soon as I get it, maybe more than a month, I let you know how I feel the difference if you still are interested.
Edited by Gauss1777 - 1/24/12 at 8:38am