They use non reference class DAC ICs that are similar to those used in AVRs such as the X6800H, C30, RZ70 and higher model AVRs, but they evidently implemented them better, using differential schemes and might have use better OPAs than those used in the AVRs mentioned. Still, measurements do show them in >110 dB SINAD rangge, that the likes of the much raved Anthem AVM90, Marantz AV10, Lyngdorf, Arcam etc. AVPs could not achieve on on the test bench so far, not even close in fact. So, there is still potential/possibility that in the future (might be distant futre), that minidsp might come up with something that could compete, but not replace, for various reasons with the high price AVPs for certain HT applications such as the low channel count applications.