In article , TT
wrote:


Now before anyone brings up DBT/ABX it would be a pointless exercise as
a slight 50Hz hum from the power supply of the chip amp is a dead give
away ;-) So even turning it on negates any unbiased test :-(

Not so. It should be perfectly possible for *both* amps to be powered, and
driven with the same input signals, symultaneously. You can also use dummy
loads on the amp you are not listening to. Thus making largely 'common
mode' such defects.

Although personally, I would not choose to use an amp whose physical hum
was audible in use. So if it did that, the behaviour would tend to make me
choose something else.

So if we forget about the power supply and concentrate on the
performance part, then I can say that the amp does a surprisingly good
job and gives the 850 a run for it's money (so speak). Mid range is
very similar but I can pick differences at either side. What I would
say though is that it does sound like a lot of valve amps that I have
heard over the years and so can understand why people would like them.

I would just like to point out that it is always difficult to fully
comprehend what someone is actually listening to on their system unless
you physically hear it for yourself ;-)

What you can do, though is:

1) Do a form of comparison which is designed to exclude any tendency for
judgements of 'difference' to be based on factors other than the actual
results emerging from the speakers. From what you say, I think this would
be quite possible in the case you describe.

2) Examine the units and understand the implications of the engineering
involved.

So, for example, if you were to use a 'gainclone' with tiny reservoir caps,
you could check to see if the output was being accompanied by levels of
ripple intermod whose details varyied dynamically with the music. If you
found this was present at high levels, it might then explain some of the
percieved 'differences'. (Assuming you were also doing (1) so could have
some confidence that they were not extraneous.)

Similarly, if the units had markedly difference frequency response in use,
that might explain any reliably-established 'differences'.

What may be difficult is knowing what someone might 'like' as their
tastes or circumstances may differ from your own. However it is far
from clear if differences *are* always as audible as people assert,
or arise for the reasons they assume.

Sainte,

Jim

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