affordable DAC for rock/metal

Are there some DACs that sound better for Jazz, Classical, books on "tape," or Folk?

Isn't the most accurate always the best?

Newbrook. Yes, most accurate is usually best overall, but not all CD's are recorded/mixed the same, and many rock/metal CD's can sound overly aggressive and annoying on many high resolution systems. Some players and dacs are known to sound more "forgiving", and the Valab is one of them. Far from the bottom line in detail, soundstage, air and recorded space, but it can be very "listenable", as far as "just enjoying some music".

Ideally, your system should sound good with all types of music, from acoustic to amplified, but that's not always the case. Throw in the fact that some CD mixes sound terrible, regardless of music type, and things get even more inconsistent. Everyone has to "balance" their systems for what works best for them, and there doesn't seem to be a "one size fits all" system, at least in my budget.

"many rock/metal CD's can sound overly aggressive and annoying on many high resolution systems"

Not sure I'd agree with this.

A good high res system only gives you what is there. Rock/metal can be a lot more difficult for a system to reproduce well than many think. You have to have good overall system synergy and component matching and amplification that is up to the task of reproducing dynamics and transients effortlessly, otherwise things become nasty, fatiguing and annoying.

Don't know if it's within your range or not, but this is certainly a stellar review of the Bryson DAC:

http://stereophile.com/digitalprocessors/bryston_bda-1_da_converter/

I like to rock out here and there... and Use some very aggressive metal far beyond metallica! But also listen to Jazz and several other variations between.

This I can say, Original recording will vary greatly. Today in the last 5 years, close to 10 years now the recordings on many more popular Rock and heavy music have come a long way from that 1989 Megadeth copy of a CD for sure. However the rule still stands, some CD's are just gonna sound great in the Car, or Headphones...

Dac's are also tuff to classify for this, almost all can play back a perfect Jazz recording or even the beatles and sound perfect. Metal is not as easy for sure, you will need speed, clarity, and warmth, neutral dacs in this case will most likely not cut it. Or at least sound as enjoyable or musical in many cases...

I would suggest look at Monarchy audios dacs, very heavy built power supplies, robust sound, good features, and fairly cheap on the used market. Also to really smooth out the excess distortions of these recordings it takes some serious jitter reduction, Monarchy also builds the device to handle this very well from personal experience, its called the "DIP" they make a standard and upsampling version. However they only build it on its own, its the top selling device so they don't build them into their DACs your forced to add another power cable and coax.

Also these devices can convert your digital to true Balanced connections which can have some good factors on distortion to the sound.

Finally don't waste to much time chasing the dragon, many cases you will never hear the full results especially in super hi power heavy distorted complex music unless you invest in perfecting your room acoustics, this really puts your dynamics, acoustic energy, and overall clarity/musicality to the test.

Good luck