DAC Upgrade

+1 @mzkmxcv

NOS will often roll off more than designs that upsample.

R-2R is inherently less linear overall and has differential non-linearities also as it is impossible to design precision resistors to the requisite degree of accuracy. Therefore you will get more correlated musically related distortion. This is a fact. This is why engineers prefer Delta Sigma for linearity.

Ultimate linearity is DSD or high resolution PCM through a delta sigma style DAC. The only issue with lower bit rates is higher noise. This is why the latest delta sigma designs are 6 bit - a hybrid between R-2R and a single bit delta-sigma which is achieved by massively parallel 1 bit delta sigma converters (equivalent to a resistor network that achieves bit depth through additionnof various resistors)

Wow! I didn't realized I would create such a firestorm of opinions on DAC's and the various technology and  formats. I respect every opinion on the board but although measurements are important, I have found that great measurements don't always produce great sounding equipment. You can see the state of confusion we audiophiles are in when it comes to buying our equipment since we now choose from a plethora of really good products. I wish I could evaluate every DAC mentioned here but that is not possible so the only other choice other than system measurements is to rely on the findings of other audiophiles and reviewers. I am sure that any of the DAC's mentioned here would make me very happy at my price range. I will continue my search for now and probably add to my short list. 
Thanks everyone for your input

@cavy

I have found that great measurements don’t always produce great sounding equipment

It usually does when doing a double-blind session (and level-matched below clipping and quick switching). Measurements don’t mean squat when you have it in your home or go to a dealer’s demo room.

My main point was arguing against clearly incorrect statements that measurements can easily prove. It’s fine to say you prefer one over another, but to state that one is more transparent when more distortion/aliasing exist, just shows the flaws of sighted listening evaluations.

Ask anyone how owns a R2R Multibit dac or cdp while playing PCM Redbook that has the ability to switch on the fly between NOS and OS, and you'll get the majority saying the NOS sounds better to them for the reasons I mentioned above, which are:

" In NOS mode with the Holo Spring dac playing PCM RedBook, there is more body to the sound, and the treble has more transparent and noticeable "harmonic" extension to it."