This is confusing a simpleton like me.
I started off looking for very powerful amps because that's what I thought the new speakers needed.
Then people here start to explain its not all about the power, and the HiFi world reviewer said he couldn't find a singlr solid state amp that really worked with the pl300s.
As a result he recommended the low power valve that he said was very good with the bass.
Now here the impression seems to be that valves won't control the bass.
Organising a home demo is time consuming, so I'm trying to focus on a handful, but seem to be going around in circles
i feel for you indus, i realy do. been here- round and round!
ill do my best to help you see my opinion at least....
1) above all else, and before anything else- you need a system that will energize a room fully, this means that you need to select a speaker that has a reasonable cone area compaired to your room.
-its much harder to have a cone area too big for a room than too small- too big a speaker is a unlikely and un-common problem, but too small is very common.....so, i know how big your speakers are, but how big is the room?
2) you need to be able to control the drive units propperly.
this depends on the speakers and 4 factors of them, they are;
a)most importantly the TRUE efficiency of the speakers-at its lowest point.
b)the MINIMUM impedence of the speakers
c)the f3 of the speaker (the point at which the bass is rolling off by 3db. NOT the commonly refered to 'frequency range' as this means next to nothing.
d)this is a little complicated, but its essentially the force available through the magnetic field (bl and flux density) vs the suspended weight of the cone and voice coil- lets leave this for now- but this becomes vastly more important if you have a speaker that is under size for the room.
now if your room is small enough, you can get away with a valve amp...yes. because your speaker will not need to move much to energize the room as its quite big....a envious position to be in in the first place as in my opinion your ahead of the majority of people!- theres a price though- you will sacrifice the lowest of bass if you go with valves regardless of what your speakers are.
as mentioned earlyer, a SET valve amp is by nature VERY low power (6-12w) and if you did go this way - i whole heartedly plead with you to have a listen to a valve amp using 300b valves- the border patrol amp is a amazing example of this.
but if your room isnt tiny- just forget it- a SET valve amp will give you a vague, overly warm, muddy, bassless, guttless dynamicless mess.
for a regular-large room to run a SET amp, you need a speaker to have 95db/w + and because of the laws of physics, this speaker will be massive.
in short- systems are forced to conform to a style baised on the sise of room vs the size of speaker.
your speakers are large (good start) but are fairly average efficiency- you can run what you like -but will likely find you will need 20w+ (solid state for good low end) or you could sacrifice a little low end and have a higher power valve choice- say 30w+.
the reviewer of the pl300's would likely be a fan of valves and grasps at the oppertunity of running a hard cone on valves-which is very very rarely a do-able combination. (my magnesium cones are a typical example of 85/86db/1w- which just isnt a valve friendly load) in fact i can think of only one other hard cone speaker that is vaguely valve friendly- avalon acoustics.
if you do go for the higher power valve examples, they dont have the magic of the SET class A amps -so the advantage of valves becomes less clear.+ they take lots of TLC to keep the sound sweet over time and require replacement valves (like a lightbulb does)
whereas there is the option of the SET class A SS amps (not many choices here) and the jungson amp mentioned earlyer is a very very good example and the cheapest also!