Best DAC for my situation...Read on!

The traditional purpose of a pre amplifier was to bring the different output levels of analogue sources to the same level (and add the massive RIAA equalization required by the phono input), to allow you to switch between these sources, to use tone and balance controls, and to control volume.
However, these days you do not necessarily need them anymore. Typical input sensitivity of a hifi power amplifier is now 2V, and typical cd red book standard output of a digital source is also 2V.
So what does one still need? Apart from tone and balance controls which you could also and better do with a mini DSP, you only need a volume control and a switch between inputs.
In a very basic system such as the system in my study, with just a computer plus ODAC usb DAC as a source, all I needed with my QUAD 405-2 power amplifier was a volume control like the Emotiva Control Freak.
With more digital sources like a basic streamer, a disc player, a tv, and perhaps a computer, one would need a DAC with multiple inputs and preferably a volume control. Examples of such units would be the Marantz HD DAC1, the Pioneer U-05, or various Benchmark DACs. Such DACs are in effect the modern incarnation of the traditional pre amplifier. Inserting a traditional pre amp after such DACs just adds distortion, noise etc. Pre amplifiers can only degrade the sound. And they are a waste of money.

I was all set on an all in one box solution for sure.
However even my stubbornness can see that while convenient it may not be the pinnacle of musical nirvana and it maybe time to consider changes.

I still think I would try a decent dac before the c48 and then sans c48 to see what I hear.

If you are lucky (and you may well be if gain is correctly matched) you will hear no difference. If you hear a difference, you know the pre amplifier is the culprit.

Yes you can choose to use a favorite pre-amp as a personal preference tone control or not. Clean and accurate alone does not always cut it for all ears. Benchmark HDR DACs are in fact DACs built into a good quality pre-amp. You can swtich between both analog and digital inputs. No phono pre-amp though with BEnchmark. You have to add that still if needed.

I have a Bel Canto C5i digital integrated. It truly has it all. Digital, line level and phono inputs, 60w/ch. The most versatile and best sounding single device I have ever owned. If it did not work out, teh BEnchmark was next on the list but I have other Bel Canto amps that are top notch and I decided to give everything in a single small box a try first. Very glad I did!