I just want to my 2 cents on this. This is my first post, my experience and equipments are not good enough to be any reference, but this is my pure opinion.
I listen my DX1000s through MAC4300V Receiver. I can detect some background noise when there is no music playback but not high enough to be heard during music played. I think the reasons are it is all in one box, therefore there is probably some interfere noise for its radio receiver leaks into its pre-amplify section, and the DX1000s are quite sensitive also. For sound it makes, it does good wide sound stage, but not depth. Singers seem like standing in the same line or one step back in stages. Treble is reveled, I could say it's too bright for me. After I listen for 20 minutes my ears are tried. Mid, as I mentioned above, is not quite present a bit too lean but I can taste some warmth and sweet from the MAC. Bass (I'm bass lover that's why I use DX1000) is good in quantity and control but not deep and lack in extent.
I wouldn't say MAC4300V is bad but due to its age (build in 1977) and all in one configuration. It is one of the best in that time but not for today and not as good for headphone amp.