Note: This could be a long complicated discussion, but rather than bore you, I'll give you my own personal 'bottom line'. I will generally be referring to active pre-amps rather than passive potentiometers. Also, I've glossed over this matter in other sections of my website as well.
- A pre-amp is something extra in the signal path. Its not supposed to modify the signal in any way, but since its in the way of the signal path, it will.
- Generally, more expensive pre-amps use better parts, better linearity, better impedances, and are generally more transparent.
- Conversely, cheaper pre-amps introduce colourations that often veil the sound. And for solid state pre-amps, introduce an electronic 'haze' over the music.
- Compared to passive devices, active pre-amps often have better dynamics, soundstage, and 'life', if the source component is very good, the difference is very small. However, passive devices have a breathtaking transparency.
- At lower price levels, passive devices will sound superior to active pre-amps. As a ball park figure, consider active pre-amps costing more than US$1000. However, it is often said that transparency requires a US$2000 outlay [though many just above $1500 are reputed to do the job well]
- Tube pre-amps are not inherently superior to tubes. They're just more fun than solid state and without the maintenance hassles of tube amps.
Pre-amp: How important?
I think that pre-amps are very important. Though they don't really do anything, they have the potential
to wreck sound quality. Therefore, either pay close attention to the quality of your pre-amp or go without
a pre-amp (like myself, though more for lack of $$$ reasons).
But one very common objection is that 'it doesn't do anything, so how come it costs as much as a power amp'.
Yes, you may have noticed that for most upper-middle to beginning hi-end system, the pre-amp cost as much as the amp.
You compare the size, number of parts, weight, etc of the pre-amp to that of the amp and wonder why you're
paying so much for the pre-amp. Fortunately, diminishing returns kick in pretty quickly for pre-amps and
US$3000 pre-amps are that much better than US$2000 pre-amps, whereas for amps, (because of the existence of really
hard to drive speakers), the extra watts (something like $50 for 1 watt? :)) do have a significant effect
on the sound.
The usual explanation is that the linestage voltage, being less than 2v usually, is very sensitive to all
sorts of things and top quality components are required to preserve the signal.
Real world issue addressed: To upgrade intergrated by buying an extra power amp?
Ok, straight to the point. If you're buying a complete system, and you're thinking about buying an
integrated amp and an additional power amp in order to start biamping, think again. You would be much better
off buying the power amp and a pre-amp that costs as much as an integrated amp. If you still have the mindset that
"if a pre-amp costs the same as an integrated amp which also includes a pre-amp, buying the integrated is
the better choice", beware... Don't you wonder why the pre-amp though made by the same manufacturer), costs
as much as the integrated??
In fairness to Integrateds...
When a manufacturer builds an integrated amp, they conceive as the integrated amp as being a 'Budget' product, and they build it that way. On the other hand, if they built an integrated amp in order to capitalise on the inherent advantages of the integrated amp (no problems impedance matching between pre & power, cut stronger signal path etc), they would certainly come up with some great integrateds. Yes, and we shall now mention the Krell 300i (used by quite a few on my enthusiast's list, including one who uses it as a pre-amp for his KAV-500 home theatre amp).
Of course, many of them know they can't build in a decent active pre-amp stage for the price, so they go the passive route. The Jadis Orchestra is passive, and I think the YBA integre is too. Of course, since they know their power amp stage is going to be used with a passive pot, the designer can take this account when tweaking the sound of the power amp stage.
But I already have an integrated amp, I have no other upgrade path
Well, I admit, that was my mistake. Fortunately, I could just shuffle my Quad 77 integrated to my other systems. (currently its the surround amp for my Home Theatre until my 14 year old Phase Linear amp in my office dies). But for many, upgrading with a power amp so that they can biamp is the only upgrade path. Rest assured, the sound will improve, you'll get more bass, slightly smoother sound throughout, but I don't think you'll get more transparency. And after this, your upgrade path ends. Unless you dump the integrated and get a new pre-amp.
Buffered and unbuffered pre-amp outputs... huh?
Tube pre-amps - more tubes the merrier? Conrad Johnson vs Sonic Frontiers :)