Burson Buffers?

The answer has everything to do with the output impedance of your 840C and the input impedance of your preamp (or integrated amp, or receiver).

If there is no impedance mismatch, then the Burson Buffer will not provide any improvement in sound.

The 840C User Manual shows an output impedance of less than 50 ohms. This is quite low, and will provide an excellent impedance match even with passive preamps.

I'm doubtful that a Burson Buffer would have any audible effect.

However, if you access to one without obligation, it's worth the experiment.

A friend and I compared the Burson to a Goldpoint stepped attenuator, using a 840C and Pass Monoblocks.

Even though the goldpoint was built with quality parts(silver wire, copper RCA jacks), the Burson had better transparency, dynamics, and extension on both ends. I would highly recommend it.

Face, what was the stepped attenuator value of the Goldpoint, i.e. 5K, 10K, 20K, 25K, 50K, 100K, etc., and what was the model of the Pass amplifier? Also, were the amplifier's RCA or balanced inputs used?

I can find out which value Goldpoint later this week, but we used the single ended input on a pair of Aleph 2's.