Tight bass in a DAC is achieved by a combination of low jitter of the interface or input signal to the DAC as well as power delivery that enables this in the DAC.
Power delivery includes power supply, voltage regulators, power storage caps and power decoupling caps. These all must be good designs and high-quality parts of optimum values. The caps in particular must have high "Q". Bass dynamic response depends on it.
The output caps affect on bass response will be minimal as long as the load is high-impedance, like 25K ohms. Even 1uFd is sufficient to get good bass. If you plug 100 ohm headphones into the DAC output, it will probably not have any bass, but any preamp or amp will be 25K ohms or higher. Not an issue.
I make a very detailed DAC, the Overdrive SX, but it also has superb bass response. Ultra-clear imaging and liquid vocals. If you don't care about DSD, the Overdrive SX is the one to beat. It does not decode DSD.
One thing that will make it difficult to compare DACs is if you are not using the same interface, for instance comparing one DAC driven from a CD transport to another using USB from a computer for instance. The first thing is to achieve a really low jitter source. Then, feed all of the DACs with this same source. Your CD transport can become this, but it will need some help. A Synchro-Mesh reclocker can reduce the jitter to around 20psec. Typical Transports have about 800psec of jitter. See these jitter plots:
http://www.audiocircle.com/index.php?topic=154408.0
Steve N.
Empirical Audio