New DAC versus higher end used DAC?

Does anyone have direct experience comparing the previous generation of high end DAC (especially Muse model 2 plus, Meridian 563 and Timbre TT-1) with newer units like the Bel Canto (1 or 1.1) or the PT-3A.

I'm trying to upgrade my front end by spending as little as possible and some of the non-24/96 DACs which were very well received can be bought for1/4 of their original price. Or am I being foolish, are the new units so much better that a new $700 unit outperforms what was a 2-4K one three or four years ago?

I'm planning on using an ARCAM Alpha 7se I already own as transport (it has the same transport as the Alpha 9se). I have the Musical Fidelity A3cr amp and pre. TMC White and Yellow interconnects Analysis Plus oval 9 and 12 in a biwire run as speaker cable to Magnepan 1.5/QRs. Power is filtered by a Monster HTS-2000 and I have a mix of Stealth HAC, Kimber PowerKord and Dedicated Audio pds one power cords.

Help would be greatly appreciated.

Thanks.