Hmm I dont think its a bad pair, they dont sound broken or anything. With a proper record they do sound better than DT880, but songs where difference is really big are rare.
But you are also right about the volume. I'm sure HDP is not doing the T1 justice, because its not a particularly good sound piece of equipment. I remember a noticeable step down in sound quality when I compared my old Asus Essence ST to HDP.
That's it right there, it's hard to find a cheap amp that can push decent power from 600-1600 ohms. I think the #1 price/performance amp for the T1's would be the stock Bottlehead Crack. IMO.