Audio Research DAC-2 versus DAC-5

Would like opinions of AR DAC2 versus AR DAC5 please. I own a DAC 5 and like it very much. It is Delta-Sigma 1-bit with 20-bit resolution. The AR DAC2 is an older unit with 20-bit Ultra Analog DACs. The DAC 2 was more costly than the DAC 5 when new. Thanks!
I own the DAC3 tubed,further than that I don't know,but I was told by few others that the 3 with the upgrates and NOS tubes is the better sounding one.I like to get some NOS 6922's but they are costly.
I am curious about this myself.i dont understand why the newer dac 5 cost less then the older dac 2 on the used market..anyone did any comparision between these 2 DAC s.
Check for info on any Audio Research product ever made.The guy who runs the site is a TRUE ARC fan and he is the one who adviced me to get the DAC-3 over the other models.