What dac would upgrade my Music Hall CDP?

If it were me I would leave the DACMagic out of the picture unless you use an optical connection, because on USB it won't do over 16/48. See the FAQ on the Cambridge Web site. (Where they say USB is inherently limited to 48KHz. It's not.)

For sonics, I think it is worth saving to go higher up the scale if you can. The Benchmark is very popular and you might like it. The Apogee Mini-DAC is actually my preference at that price, though.

Even though small upgrades are fun and teach you things, they are potentially more expensive in the long run than a single big step. If you want to squeeze more out of your CDP (which is very nice for the price), and you haven't tried tweaking it with a premium AC cord, antivibration footers, an isolation transformer and all the rest, well, consider that. After you upgrade, many tweaks can still be useful, or be resold without much loss if you buy them second hand.

The V -DAC is one of the better ones on the market period. Get one and try it, all you can lose is return freight if you get it from Audio Advisor as they have trial period.

look at MSB Tech

I've not owned the vDac but someone I know is in the business and they've been flying off the shelves since a recent Stereophile review. No returns either. Customers with whom she has spoken think very very highly of this sub 300 product.

Read the article.

I bought a V DAC and it is as good as the tests would indicate. HIFICRITIC said that they had never seen a product this cheap that could compete with the best available as it does. They used it with digital ICs that cost twice what it did. The system I am running it in would be about 30K at current retail and it holds up its end.