Stan, having owned every version of the Sigma and Alpha DAC's ever made, currently owning a highly modified GDA-700, having listened to a fully modified Dio from Bolder Cables, Bel Canto and MSB along with the newer Musical Fidelity upsampler, i would look for an EVS Millennium.
In specific, i would try to search out a Millennium 1 or 1A. I would choose one of these over the Millennium 1B or the II for your specific listening tastes. The original Millennium 1 or 1A has phenomenally holographic vocals. One can plainly hear the differences in transport and digital cable quality with any of Ric's DAC's if properly set up. Much of what people may attribute to being a flaw of the DAC is actually the limitations of the transport and cable being passed on. You can typically find these for $300 - $400 on the used market and would have to spend a very considerable amount of money to take a sizeable step forward ( in terms of a DAC ). The naturalness, liquidity, depth, air and sense of ease that music seems to flow out of these units is amazing. If this were a "big name" product, it would have retailed for appr $4000 due to cost of internal parts, manufacturer's profit margin and dealer mark-up.
The ARC units are very fine DAC's also, but are leaner sounding / lack the natural bass "bloom" that one hears in the warmth region and lack the bass extension that Ric's unit really makes noticeable. One can play with tubes to try and achieve this with the ARC units, but the cost of the DAC and an assortment of tubes is FAR more costly than what you can find an overall better performing and less costly EVS for. Believe me, i was going to go that route ( DAC III ) until i really started checking things out.
I will only add that the EVS' are limited to having one input only i.e. you can not hook up multiple digital sources to the DAC and switch between them like you can with the CAL's, GDA-700, etc... So long as you only have one digital soure or don't mind swapping cables, this should not be a problem. Sean
Sean- Millennium II fed by modified G&D UTP-1 Transport
My brother - Millennium 1B fed by modified Pioneer PD-65
My father - Millennium 1A fed by modified Philips Transport