Bill - these older D/A chips are very musical, but simply not as accurate as the modern designs, as well as not supporting higher sample-rates. I offered a ladder-DAC tube output DAC myself for several years. It was very sweet sounding, never harsh, but never really live either.
I consider the digital filter in most DACs to be the #2 impediment for good digital playback (jitter is #1). These older chips solve that problem. They usually don't incorporate any digital filter or force the chip to automatically select a filter. They make it possible to have only an analog filter and no digital filter.
The problem is that even if you only care about 44.1kHz playback, the HF transient response of these older chips is just not like the live performance. The attack and decay never seem to be like the live event.
The is why in the Overdrive DAC (one of Matts picks), a newer technology chip was selected that supports up to 192kHz, but allows one to manually select the digital filter. I recommend to select only the 192 digital filter (there are three) on the Overdrive, even when playing 44.1kHz tracks. This is how I use it. This approximates what these older chips do at the same time delivering accurate transient response.
A number of companies have gone to extremes over the last 10 years to develop their own digital filtering techniques, in order to eliminate or reduce pre and post ringing on impulse response of their DACs. This was an effort to improve the deficiencies in digital filtering in off-the-shelf D/A chips. So far, I have not been impressed by the sound of these filters. I still believe minimal or no digital filtering is best.
There are a couple of modern D/A designs that use the old R2R ladder technology, but also support higher sample-rates. The TotalDAC and the DaVinci II are such designs. I have read great reviews on both, so they evidently have decent transient response.
Steve N.
Empirical Audio