It had to have occurred to Meridian that by only including a USB digital input, they've greatly limited this device's functionality. The Director, at only half the cost, managed to include both USB and SPDIF. For a unit that costs $2000, they should have been able to include both an SPDIF input and a pass-through SPDIF output.
It's interesting to see the inclusion of ASP, which Bob first employed in the 601 preamp from the early '90s. I enjoyed the 'out of the head' imaging offered by that unit with HD650s, and I have no doubt that the implementation here is far more accomplished.
I'm surprised that there's no SPDIF input, but if market research suggest that USB is the dominant carrier method these days, I'll accept that. It looks like a very flexible unit indeed, and the availability of the upgraded power supply (with outputs enough to drive several devices) takes us nicely back into Lego for Dads again!
To echo Frank's comment, a matching phono stage would do the trick nicely. The bottom shelf of my rack contains Musical Fidelity's trio of X-Canv3, X-PSUv3 and XLPv3. Meridian have just ticked two out the three boxes for me...
I'm surprised that there's no SPDIF input, but if market research suggest that USB is the dominant carrier method these days, I'll accept that.
Perhaps Meridian's market researchers should have looked at Meridian's own components, none of which, to my knowledge, has a USB output. Yes, they have analog outputs, but I think my G91A converts all inputs to digital. I hope I'm wrong about this, because otherwise listening to an SACD through the Prime would involve two A/D conversion stages.
I'd be curious to know how many other DAC/headphone amps in this price range lack an SPDIF input.
Just to prove I'm able to see the glass as half full, it's good to see the Prime will power balanced headphones, although it wasn't clear to me that the Prime was itself internally balanced.
I see there's some interest for having a SPDIF input, the major problem with this is that it would introduce constant digital noise to the analogue circuitry harming its performance. The best results are achieved with multiple boxes to isolate noise, this is reflected by the double skin design of Prime.