Hi Newbee,
The faster we go, the rounder we get ... It's difficult to understand exactly what you're running from your system description.
Do I understand you that you have relegated the ARC SP10 (a full function preamp) to phono stage duty?
This is a classic piece, which I've admittedly not heard in a long time. My gut tells me that this was the high water mark for ARC and it was all downhill from then. Your SP-10 will certainly bring a pretty penny and open up some cash for you to change directions.
If I had to shoot from the hip on this one, one recommendation I'd make would be sell it all and buy a Supratek Cortese (1 year wait).
None of this is to dismiss your PrimaLuna, which I've never heard, but looking at Upscale Audio's site, I have to wonder about the decision to spend money going dual mono with this design instead of going with some better parts. Solens are very pedestrian capacitors, and in my experience, I've always found a stereo implementation to be better than a dual mono implementation at a given price.
Had they stayed stereo (not as good from a marketing perspective) they could have used some better parts. Now, I'm not about boutique parts when they're not necessary, but I find it odd that they would brag about using Solens. If you keep the unit, you might want to investigate swapping some Teflon coupling caps in their place.
Assuming that you don't get a Supratek, and that you keep the PrimaLuna, get a Hagerman, Artemis, Ear, etc..
Another alternative might be the Monarchy M24 DAC which has a built in line stage http://www.positive-feedback.com/Issue25/monarchy_m24.htm
Lynn Olson loaned me his unit for some two weeks. When we upgraded the volume pot (feeding it with an autoformer based volume control), this was a very, very good line stage.
As an analog guy who builds turntables, I've fairly well ignored digital "breakthroughs" of the past decade.
Because of this, I can't comment from a broad base of listening experience. I can tell you that every SACD I've heard has left me "musically empty", that the $15K Meitner DAC has been uninspiring at best. Other digital experiences have been similar - having from good to great "sound" but a reproduction that I considered to be musically irrelevant and uninspiring.
Lynn will tell you that I'm just not accustomed to listening "through" digital's problems. While this may be true to a large extent, my experience of the Monarchy DAC makes this a question I no longer need to wrestle with, because I will be ponying up for one of these DACs in the near future. It carries the musical load.
I need to make it clear that I have no personal interest in making the above commentary.
Following this architecture might keep your box count identical (after adding a phono stage), and may well upgrade your digital as well as your analog signal path.
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Having said all of that, I have to wonder how well your turntable is set up. You should be enjoying a rig like yours (Oracle, Sumiko, Benz Glider). Perhaps you have a small record collection, a curious toddler, or a hyperactive cat that precludes playing vinyl?
Cheers,
Thom @ Galibier