Not only does the Keithley 2015 have a THD analyzer, it has, as a part of the THD board, an audio signal generator up to 20kHz through a BNC out the back. Also, there is a "timed-scan" recorder with ten registers to, for example, capture a discharging battery voltage over several days. It is a nice DMM that I use frequently on my bench. Noise is not a problem for my lab as there are several meters, etc. running 24/7 so one more is hardly noticeable. For a 6.5 digit meter the 2015 is very nicely priced; mine was well under $400.