what impacts the sound quality more amp or pre-amp

which component has the greatest effect on sound quality, the amp or pre-amp? does one invest more in pre-amp to achieve sound quality?
To answer your first question:
Whichever is the weakest link.

To answer your second question:
Everything counts in the system chain, from the source, to amplification, (pre and power), to the speakers, (and even the cabling can have a big impact). System synergy is everything. So a balanced approach is best, IMHO.
It's about interface with the surrounding components. The pre needs to have enough of the right inputs and outputs, perhaps be able to handle your given cartridge(s), have an appropriate output/volume control and output impedance for the amp. The amp need to have the right input sensitivity and input impedance for the pre, and the right power output and impedance handling for the speakers/room, and perhaps the appropriate output taps and number of binding posts, and oh yeah, they have to sound good together! With all that said, and being in complete agreement with Kurt, and though you'll probably have more hands on with the pre, IMHO the amp is usually more important.
as typical we i am always looking to improve the sound of my system with a budget in mind. That being said, I was told I would get more bang for the buck in investing on the pre-amp side of things and keeoing my existing amplifier. I have a SS system using B&K components and desire a more natural or as they say tubey sound with a larger soundstage. My budget is 500 - 800. My impression is I would do better by buying a Prima Luna 3 pre-amp versus purchasing a hybrid amp such as a MOSOCODE 300???
As others have stated above, all components within a system matter, the weak link will drag the overall performance down every time. But to answer your specific question, in my experience I`ve had more profound change in the sound/character of my systems with power amplifiers more so than preamps without exception. The transition from solid state to push pull tube and then SET-DHT amps were major steps.
I think a high quality sounding preamp can carry a mediocre amp and visa versa. But without question you will want to eventually upgrade any other inferior component(s) to get the desired sound you are ultimately seeking. I would tackle the preamp first since its job is the toughest and it is one of the hardest components for a manufacturer to get right. To find one that sounds decent within a certain budget can be difficult but not impossible.

A few years ago I owned some B&K components & liked them but found out that some of their models stand out more so than others in terms of sound quality. That would include some of their older gear.
Everyone is correct and its obvious they have all had vast experience in this hobby. If I were you I would upgrade my preamp first, you might look at some used CJ like PV10 in particular.

You get a real bang for your buck and you get very tubey sound but totally grain free and non-fatiguing. Just an option.
Dvdgreco, if your looking for advise on the best bang for your buck system improvement, why not post your system? Be careful of advise touting personal technology preferences without considering your personal budget and system.
my system is

B&K ST202 (I think its a sonata series??)
B&K 10ProMC
Alon II speakers
Jolida 100 cd
Are you sure that you want to rule out an integrated?
Personaly, I don't consider separates unless I am prepared to spend thousands, at least couple of them.
The Alon II speakers are specified as 87 db efficient and are, I think, 4 ohm nominal impedance. This is a difficult load for most tube amplifiers to drive.

My personal feeling is that if you want tube sound that you should go with a tube amplifier. I think this makes the most difference. But it implies certain speaker choices too.

From a practical point of view, it is going to be challenging to find a tube amplifier for $500 - $800 which will be able to reasonably drive your speakers.

In the context of your system and with your budget, my feeling is that a tube preamp would be your best bet.

The Mapletree Audio Line 2A SE preamp is $760 new. It will likely survive many system changes and upgrades that may or may not be in your future.
"The Alon II speakers are specified as 87 db efficient and are, I think, 4 ohm nominal impedance. This is a difficult load for most tube amplifiers to drive."
No mention is made of phase. This would be the deal breaker for tubes, that and wide swings in impedance.

4ohm and 87db are nice, but not deal breakers for tubes. Harbeth, less sensitive and considered tube friendly.

Tube amp choice, however, DOES imply certain speaker choice.
pre is the heart of the system. As said balancing it all out helps more.
I think the choice of speaker and then the choosing the amp
to drive them is the most important choices in building a
system; other than the recording and the room, they will
have the biggest impact on the overall sound of your system
- the change brought by digital source and preamp, while
important do not make nearly as much of a difference as the
amp/speaker in my experience. I also agree with Wilysnet
recommendation on an excellent tube preamp selling for a
fraction of the cost of its acoustic competition, though if
I had a tube amp I would go with the even less expensive
Lightspeed Attenuator $450 which is the best sounding volume
control tool I have ever heard if well matched to an amp
(though not very flexible with only one input/output, and no
remote control.

So yes, everything is important....but the amp/speaker is
critical and the most defining pairing for what you system
sounds like. Once you get that right, the rest is relatively
easy (though not foolproof).
would a moscode 300 hybride tube amp pair well with my system?
It would drive your speakers, but seems like a lateral move from the B&K, I would also worry about such a old amp unless it gets the once over by a tech and possibly its capacitors replaced - it is a early 80s amp - no?

Could you describe what it is that you are trying to change with the sound of your system? Something you don't like about what you currently have that you are trying to improve? That B&K amp is a pretty nice SS amp.
looking to get more silky mids and highs, larger soundstage.. the original chinese tubes in the jolida were nice but too loose in low end
I think you would be well served by trying the Mapletree Audio preamp previously mentioned $760 new, $800 with Blackgate Capacitor upgrade (Made by a retired E.E. Professor/Audiophlie in Canada). I think you would get the kind of change you are looking for as you described it. Do you know the input impedance of ST202? Should be OK with the Mapletree unless less than 20kohm. The Mapletree is wonderfully smooth and full of tone with its use of the 12sn7 or 6sn7 tube.
My memory could be failing me on all this, I could be mistaken, but if I recall correctly the B&K's ST series, had a rather low input impedance, and a low V input sensitivity for full output. Both of which can make matching a tube pre to a bit tricky. Another concern might be the ability of the B&K's non + ST series of amps ability to handle 4 Ohm loads well.
The nominal impedance of the IIs was 8ohm with 4 minimum. I think the input impedance of the B&K amps was the odd 33.2 kohms (you really have to double check with B&K), the Mapletree get be set with 0-10db or 10-20db gain, so sensitivity should not be an issue, I do think the B&K amps had sensitivity of 1.4v, but should not be an issue with an active line stage.
The nominal impedance of the IIs was 8ohm with 4 minimum. I think the input impedance of the ST202 amps was 24 kohms, the Mapletree has 500ohm output impedance (should be OK)get be set with 0-10db or 10-20db gain, so sensitivity should not be an issue, I do think the B&K amps had sensitivity of 1.4v, but should not be an issue with an active line stage.
I checked my facts for the second posting.
It's hard to say. It really is all about components working well together. A relatively modest change in a system that contributes to better synergy can have a much greater effect than a more ambitious change that doesn't improve synergy.

One way you can be assured of a synergistic relationship between the preamp, interconnect and amplifier functions is to buy an integrated. Also, everything else being equal, you should expect better build quality and parts selection in a thousand dollar, single chassis integrated amplifier than a thousand dollar preamp, amp, interconnect combination.
I'm happy to stand corrected. Generally, I've been choosing efficient and easy to drive speakers to pair up with comparatively low power tube amplifiers. It didn't occur to me that Harbeths, for example, are relatively inefficient but remain easy to drive.

I realized that the numbers I was giving for efficiency and impedance were actually for the Alon IV. Having said that, I can't find Alon II measurements and specs. However, I did find this thread:


Where at least one person says these should be tube friendly.

Personally, I'd go with a tube integrated amp, or a tube power amp with a passive preamp. You still need to pick the right amplifier of course to get the sound you want as not all tube amps sound the same and there can be striking differences between them.
Pubul57 is correct about the 8 ohm nominal and 4 ohm minimum for the Model II. Here's a link to the Alon product manual. I don't know what year it was published, but it was during the production of the Phalanx and before the Circe. The Phalanx was one hell of an ugly speaker.