Should I eliminate my preamp?

You need to listen to it both ways. I have a DIY model that has bit perfect volume built in. Meaning I should be able to use the volume on my laptop and the dac continues to produce bit perfect sound to my amp. I have driven my amp with this dac as well as 2 others, but when I run the dac through my Coda preamp, Everything improves. For me the Preamp Stays

Ralph Karsten (Atma-Sphere) has in a few threads here lately discussed the issue of the benefits of an active pre-amp in certain system set-ups vs. the penalties. If you can find them in the Audiogon Forum, you will learn all there is to know on the subject. Ralph really covers all the trade-offs involved between the two approaches, providing all the facts necessary to help one decide which approach is better for a given system. 

In this particular case, its a bit of apples and oranges.

The ARC is single-ended, but the Oppo has balanced capability as does the amp.

The simple fact is that balanced often sounds better because of improved cable immunity, and that the amp might sound better driven by a balanced source.

The ARC OTOH is getting a bit long in the tooth- and is certainly old enough to have filter caps failing as well as tubes.

In this case, I'd be all about dumping the preamp until its serviced out, but that is not to say that an active balanced preamp would not be able to help. Right now there are a few too many variables to be scientific about it.

This is exactly what I recently did. I bought an Oppo Sonica DAC and asked myself "what do I need a preamp for?" Like you, I have an ARC pre-amp (SP-6B) but since I no longer listing to vinyl, I was just using it as a volume control. The Sonica DAC has a perfectly good digital volume control which sounds fine to me. Plus, the Sonica DAC has balanced XLR outputs, and my Rane AC22B crossover has balanced inputs. I noticed a marked improvement in quiet when getting rid of the SP6B and it's single-ended interconnects, and moving the the DAC/Crossover/balanced XLR setup. How could an extra piece of gear in the signal path improve anything?

My SP-6B recently came back from service at ARC, and I'm am wondering if I should sell it. There are a lot of new vinyl fans out there who might want it (along with my SOTA Sapphire turntable, Linn ITOK II tonearm, and the Dynavector Karat 23R cartridge).