what is the best, least costly DAC...?

If your V-DAC sounds dull and lifeless then I would suspect the digital cable or transport. I admit that it makes little sense to use a $1700 digital cable[Transparent Reference] with a $300 DAC but it works for me. I have found that the cable makes a very considerable difference. HIFICRITIC has tested both the Saturn and the V-DAC, they gave the Rega a score of 29 and the V-DAC 42. For comparison the Benchmark DAC scored 22, the V-DAC got just about the same score as a very expensive DAC from MSB which is close to $10000. They think it is one of the best buys in audio.

So you've had the RAM mods (including the Audio Consulting output Transformers ?)
All you now need is the Vacuum State Terra Firma Lite co-designed by Custom Analogue Audio.... this along with some other enhancements installed by CAA transformed my Saturn by an order of magnitude.
Forget the V-Dac and most others of even 8 times the price, the dual Wolfson 8740 dacs in the Saturn are damn excellent, they just need a PROPER PS and clock PS to really let you hear what they are capable of !

http://www.customanalogue.com/terra_firma_reviews.htm

http://www.customanalogue.com/terra_firma.htm#Terra%20Firma%20Player%20Upgrade%20Description

http://www.vacuumstate.com/fileupload/VSE_Clock_Upgrade.doc.pdf

The V-DAC was demoed in several systems that are anything but dull and involving. I know the room very well too, and that wasn't the issue...

Mac seperates and transport with Sonos Faber Cremonas, and BAT and B&W 800 something or other towers. I didn't check the cables, but I'm sure that wasn't it either. When the CDPs' analog outs were used, the life came back.

Everyone likes what they like. What one finds dull and lifeless, another revels in its glory. There's no right or wrong. The V-DAC does a lot of things right. It's very good for it's price. If it had a boogie factor to it, I'd be all over it. It's no Rega in that regard. Rega's typical customer is looking for more than just soundstage, imaging, etc. Is there a way to quantify groove?

And yes, I'm a Rega owner and fan. I haven't heard a budget, so-called giant killer DAC that I would contemplate selling my Rega Apollo for. Not even close IMO.

I don't think the dacs being talked about have apodizing or MP filters. I think the PS Audio PerfectWave DAC is the lowest price dac with these filters (but it is not a low price dac).

The Perfectwave is a good dac. There are many comments from owners on this forum and some reviews on the web. Definitely check it out.

To chime in on some earlier comments on Wyred (DAC2) vs. Weiss (DAC2 or Minerva): I just compared the two in my system for a full evening and have to say that both DACs are excellent at their respective price. The Wyred is very detailed, dyncamic, extended and punchy with great stable images. The Weiss is not quite as punchy (although I still find it more dynamic with better bass than many other DACs), but still is a little more finely detailed, rich, incisive and refined compared to the Wyred.

I do prefer the Weiss for it's slightly more even handed presentation and analog like quality. Nevertheless, at half the price the Wyred is excellent value for the money.

Note: The above comments refer to a comparison of the DACs used via Firewire or USB interface with a Mac Mini.