What's the purpose of a preamp?

[mikmas]

Since most -if not all- sources (e.g. DAC, CD player, phono stage) have an output voltage, that's capable of driving a power amp, then what's the purpose of an active preamp?

Doesn't a passive attenuator seem like a simpler, less intrusive and 'cleaner' solution of controlling volume, instead of an active preamp?

In my experience - yes, but opinions are always quite strongly divided on this topic (as pointed out)

I currently use a simple 'voltage-divider' attentuator in my second system between a DAC and my Quad 303 power amp and can find no fault. In the past I have also had a similar set up with a Quad 405-2 and found it equalling the Quad 34 pre-amp it was originally paired with and had no problems at all.

BUT you need to note that these are both Solid State power amps and quite sensitive (0.5v input) so may lend themselves easily to this as opposed to your Croft tube based blocks. The divide in opinion also seems to be drawn along these lines quite often (i.e. tube v SS) although not exclusively.