I would like to hear your experiences in comparing external DAC's to those in the 990.

I'm thinking of funding either the 990 or the next Generation processor with the funds I can get from selling my Channel Islands VAC-1/VDA-2. Since I have not heard the 990 DAC's, I am wondering if anybody has experienced a direct comparison. Will I be taking a major step down for music??

My current set up:
Outlaw 7500 (amp)
NAD C162 (pre-amp)
Paradigm Studio 60's v.4
Squeezebox (SB3) + CI Power Supply + CI VDA-2/VAC-1
Entire music library in FLAC

Since I plan on using the funds from the sale of the VDA-2/VAC-1 combo, I am wondering of other's experiences. I'm ok if it is a small step down, but nervous that it will be drastic.

Any opinions??