This is true, most DACs have USB as an afterthought. If you have a computer with only USB, you need to put in a S/PDIF card or go with an external HiFace interface.
If it is only USB that you are looking for, then might I suggest the JKDAC32? It doesn't look like much, but this DAC has no upsampling, uses a Burr Brown chip and goes all the way up to 384 KHz resolution. The sound quality is supposed to be similar to vinyl. Please see reviews especially the 6moons one as well as a comparison of DACS in the sub GBP 1,000 price range. The JKDAC32 has done well against the M2Tech Young and in fact John Kenny's JKSPDIF is preferred over the M2Tech Hiface Evo.
For something that will tick all the right boxes, the Audiolab M-DAC has done extremely well. It even has a preamp that the JKDAC32 does not and the OLED display should guarantee a good WAF. The M-DAC has done better than the Rega in some of the reviews I have read.
If I am not mistaken, the Peachtree DAC is in Class A as per the Stereophile review.
I have not heard any of the above and would be interested in participating in joint hearings, etc. if anyone is in Bangalore.