the OP wanted some recommendations for a Pre.... poor Chaps head must be spinning!:(
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the OP wanted some recommendations for a Pre.... poor Chaps head must be spinning!:(
Ok I recommend the exact thing he says he doesn't want which is a passive attenuator.... I'm using one with a Radford STA25 of a customers at the moment and it sounds amazing. Alternatively I can build a wide range of active line stages to order, there is more info on a specific valve hybrid pre in my trade area which is both active AND passive (it has separate active and passive outputs).
I cannot see how a resistor network (passive) can possibly change dynamics if the FR is flat.
It is conceivable though that an active produces artefacts which may add to the signal, increasing peaks, and hence appear to be giving a greater signal range, that is, dynamic range.
As I said earlier it is not possible for an amplifier to change dynamics unless it is distorting. A passive can not change them at all as it never distorts. Only compression can occur and the this would have very obvious distortion with it. An amp running out of power and clipping is the most obvious example. If a 10W amp needs to produce 15W to reproduce the peaks well it can't do it so anything beyond 10W will be huge amounts of really nasty distortion rather than increased volume.
Can't argue with the fact that on the face of it a passive pre can't add distortion but aren't there other factors involved? For one, not all passives are equal and it seems that what's connected to the volume knob does make a difference, at least in price! i.e. all attenuators are not the same.
Second point is impedance matching. Over the years I've used three different passives, one home made and two commercial ones. The best result (to my ears) was when I got hold of a Nelson Pass B1 buffer which I believe (I'm definitely not an electronics expert) improves impedance matching between pre out and power in. This surely makes a difference?
Once again like I said earlier... there is no such thing as impedance matching in hi fi and 90% + of the time it's actually resistive rather than impedance, at least at audio frequencies.
Ah I see Jez already did.
Way too many misleading ( again ) generalizations:
A digital SPDIF or AES/EBU output input, is an example of an impedance matching network used in hifi.
Twisted pair interconnects match to usually 110 ohms and coax to 50-75 ohm , also used in hifi
A turntable cartridge has defined impedance matching to an RIAA network also used in hifi
A speaker has a defined impedance -often not matching to an amplifier but occasionally gets close -
ie Quad 303 and ESL57 also used in hifi, need I go on ?