Best DAC for my situation...Read on!


So thoughts and opinions please.
What I have and my idea.
Oppo 105D and Bluesound Vault 2 feeding into McIntosh C48 preamp.
I chose the C48 because it is a nice complete all in one box solution, headphone amp, mm and mc phono amp, lots of analog inputs with 2 sets of xlr inputs AND 5 total digital inputs.
Now I have both the Oppo and the vault connected by analog and digital inputs to the C48 so I can compare modes pretty instantly and I have to admit both cases the analog sounds better.
Which makes me wonder if the C48, although a great all in one solution may be the hold up as far as the DAC performance is concerned.

What I was considering as a trial is a seperate DAC that can handle the digital signals from the units and then output the analog signal via xlr preferably, back to the C48.
At this stage I have no intention of getting rid of the C48 as I really like the analog signal SQ as well as the headphone performance.

Any good suggestions in the range of $2000 used or am I really not going to see much improvement at that price range over the C48 capability?
128x128uberwaltz
Look into the Digital Amp Company DAC (DAC DAC)  coaxial input and XLR Balanced out. I have the TS version and love what it does. Loads of detail without being strident and clear clear bass. Tommy is a great guy to deal with and he has a very fair return policy.
Your phone as a dB meter is not good enough, I am afraid. With such small but already important differences you really need to use a Volt meter. I appreciate that complicate things, but there is no alternative if you want a reliable answer.
There are three possibilities here, I think:
1 once the levels are exactly equalized the perceived difference disappears.
2 there is a gain mismatch between source and amplifier. This could be inside the amplifier, between the digital stage and the analoguie stage, or between the DAC and the analogue input. If the amplifier clips slightly, this may sound more lively and involving, even if in reality what you hear is distortion and compression.
3 one DAC is really better than the other. In this case, with two good ones, I doubt it.
Finally, why do you think that if the the inbuilt DACs of the Vault and the Oppo sound better than the DAC in the C48 you need yet another DAC?
Assuming that the volume levels are matched, there is no gain mismatch (likely not if you can use the volume control on C48 throughout the mid range for different levels), then it seems that you prefer the sound of the two sources via their internal DACs over the C48 DAC. 

The question then becomes, "Is this satisfactory?'. 
@willemj 
To answer the latter part first
I do not believe that the inbuilt DAC in either the vault or the oppo are the last word in DACs by far and if I prefer their sound to the DAC in the C48 then quite likely a true dedicated DAC could sound only better. To my ears in my system of course.

@mesch 
Are they satisfactory?
Probably an impossible question to answer in our never ending struggle to gain improvement...lol.
Yes I prefer their sound but as above, is it possible even better results await with a separate dedicated DAC.
Like a Schiit or something.
I guess that is my problem to pondering any suggestions to ones to trial would be worthwhile.
I don't doubt that an improvement can be made using an external DAC. With a budget of $2000, and the fact that your sources output SPDIF, I would consider searching for a somewhat older DAC known for possessing a robust power supply and excellent analog output stage. These can be had at a fraction of the original price. 

Now, which ones to consider? I feel I am not one to make a recommendation here, for lack of hearing many (most) of the possibilities. I am using a Bryston BDA-1. It has several SPDIF inputs, and  at the time of purchase I prefered the use of an external USB/SPDIF converter.