Which has greatest influence?

IMO, all system components should be matched as to level of performance. A $20,000 preamp will make little or no difference in the SQ of a $5000 system.

However, the speakers need to be driven by adequate amplification. That is more important than the preamp as far a SQ goes. Once that is achieved, then attention can be given to the preamp. Unlike an amp or the speakers, the preamp will determine the type of control one has over the system. Does one need tone EQ, remote control, phono input, computer input, headphone output, etc...?

Mike

Having just upgraded my amps and then my preamp, I found them to be roughly equally important, but each effected the system in profoundly different ways. For me it came down to what the amps do and what the preamp does not do. My new amps control my speakers much better than the old amps did. Bass is tighter, deeper and more focused. Dynamic range increased as well as improved soundstage size and definition. My new preamp gets out of the way much better than my old pre did. It is quieter and more neutral. Micro and macro details improved, timbre and transients improved. However, each upgrade made the listening experience more involving in roughly equal amounts. They are from the same manufacturer, so they work very well together. My system is built around my electronics. Its the only area I have really upgraded over the past six years.

Having said that, I have found the most critical component/relationship is the room-speaker interface. This is about scale, placement and taste. Then the speaker-amp/cable. And finally the amp-preamp. The front end is a completely different thing and can be thought of as its own system(especially analog). It can be of equal or better quality but is not as interdependent as those other components are and can be thought of independently from the rest of the system.

At least, this has been my experience having just upgraded my electronics.

In response to Newbee: You asked several questions in your post which I will try to answer: Re What I meant by 'boost' I wish I knew the vocabulary of the audiophile. It simply opened a richere, fuller sound, larger soundstage, a feeling of being closer to the real thing. I was just wondering if the changing of pre amp would open that door even wider. Sorry my finger slipped when I tried to identify my new amp. It is a Conrad Johnson LP 70S.
And I think the impedence rating is 100. Would appreciate any thoughts y0u might wish to share wirth an old duffer who just t`urned 90. Jack North1178

An old duffer who turned 90 or finally hit 90? More likely the latter I think. :-)

I do believe you could improve your systems sonics with a different pre-amp.

I use the PL3 with a PL5 and combined they are excellent lacking only a little bit of ultimate resolution and deep bass power. BUT, seperately, the PL5 is deficient in the bass when driven by other pre-amps I've tried, and the PL3 is somewhat dark and closed in with the other amps I've matched it to, including tube amps with a high input impedence (I assume yours is 100K, not 100, and a technical impedence match would not be a problem).

Now what pre-amp and how much money you might want to chase after it is another thing, but you should try some out. You might try out one of CJ's pre-amps that compliment your amp.

Hope that helps a bit.