DAC bits?

It describes the number of bits of information the DAC can handle for each recorded sample.
Audio CD's are recorded at 16 bits, while DVD-Audio are (or can be?) 24 bits.

Some useful information in here: Audio bit depth - Wikipedia, the free encyclopedia

Yeah, 20 bits is fine...you're describing a DAC that upsamples 16 bit audio to 20. It pretty much adds four bits to the data. Think of it like computer monitor resolution settings. If you have a 800x600 image, and your monitor is set to 1600x1200, you have twice the image resolution, but the original image will be smaller looking, it doesn't look "twice as good". It's still the same image, but you can view it double size and it looks the same...well, with a 20 or 24 bit DAC, you're adding "headroom" to the music, but it's going to sound the same (for all intents and purposes). An upsampling DAC just allows for a wider dynamic range, but you're not going to get that out of standard CD. You'd need that for SACD or DVD-A. Sorry, that explination may make things more confusing...

The number of bits is just marketting on cd players. Listen to them both, and use how they sound to decide which is better

As far as I know, most CD players to do not increase the bit-rate. Upsampling usually only applies to the sampling rate. 20-bit vs. 24-bit won't make a difference if you're only playing 16-bit CDs. The internals of the DAC chips and CD players will make more of a difference than the bit-rate designation itself.

Good answer, but I'd like to understand it better.  I have two ways of playing a CD, both lower mid-fi: an Onkyo MC35TECH mini system and a Pioneer DV-490S DVD player.  (I chose that particular Pioneer because it was modded to be all-region, and I play foreign language films.  Only as an afterthought did I start listening to music on it.)  As much as it might horrify people to hear it, they both sound quite good.  The Onkyo is 1-bit and boasts about that.  The Pioneer is 24 bit.  I'm not sure which is better (at the moment, the Onkyo, because its amplifier is much better than what I've been using with the Pioneer.  That may change, as I just ordered a KICAS regular from Purity Audio.)  But I am sure the Pioneer is not 24 times better than the Onkyo.  

 

Another metric that gets thrown around is the sampling rate.  The Pioneer is 96 KHz.  I see that better models are at least twice that.  I can easily understand that more sampling makes for more detail.  The Pioneer isn't bad for that actually, and what it's quite good at is sound stage and tone (though I can't tell how much is my amp.)

 

When I recover from recent purchases, I might spring for a better CD player, but I'd like to understand how to judge the statistics (since I don't have a way of actually listening to players I would have to order over the Internet).  Thanks.

You may be getting confused by the specs. The way 1-bit DACs operate is quite different from 16/24-bit DACs. In general 1-bit "Bitstream" DACs were popular in the '90s, especially in portable equipment, because they were cheap and didn't sound awful. The Pioneer DVD player advertises 96 kHz as its maximum supported sampling rate, which says nothing about quality. If you put in a CD, it will decode at 44.1 kHz because that's the sampling rate of a CD.