Speaker swap or Amp,which impacts more????

What you like/dislike about your current setup?
For all you know, it could be some other things you can improve. 4 BST is pretty solid amp. Quick pace, great for recording industry. A reasonable match with B&Ws.
As far as SF line 2 goes, there are plenty of room to move up from there if you can live without the remote.

If you haven't considered room acoustics you should. This can have a very big improvement and the cost is excellent for the gains received. Also a Behringer DEQ 2496 can help alot. Otherwise I'd have to say speakers have a greater impact on the sound. At minimum read what others have said when it comes to room acoustics and learn what you can. This is VERY important if you want good sound. The average room has dips and peaks of plus or minus 15db! That is a huge non linearity in music reproduction.

You have a good amp and speakers. Being new you should listen to us old farts. If I had it to do over again I would have learned about room acoustics decades ago. Once you get that right then you'll be able to appreciate system improvements much more.

never once thought of swappin' the line2 ???? do pre amps affect sonic that much???? what i am lookin for is a little more bass for one with more headroom.is the line2 the weakest link here? all i know is i am not educated enough in hi-fi,sooo any help appreciated before i pull triggers and spend in vein.

The preamps has a lot to do with sonic character.
That's why some purist prefer not to use preamp. However, if your source doesn't have enough gain then it would sound lack of dynamic. I'm not a big fan of passive preamp for that reason.

You are missing out on the great preamps. You'll find that most of tube preamps doesn't go as low as SS counterparts. However, most of tube preamps sounds more open than SS.

If you plan to go with balanced setup,
the Audio Research LS-5 MK III is still one of the good preamps.
For non-balanced RCA output,
Audio Research SP-8 MK II and SP11 MK II do get great bass.
The SP-8 is not as clean and transparent sounding but it is warmer sounding.

If it is warmer tone you're looking for, you can also consider many other good preamps out there.

I'm in the amp camp and have found big changes there, even within a manufacturers lineup. With my current spkrs, I've worked my way from the entry level amp to the top offering and my system has benefited with a bigger soundstage, more detail, more bass impact & definition, along with a smoother midrange.

Of course, w/o a good room, the best sounding system will sound like mud and that should be of prime concern before you start swapping gear. There are simple things you can do, the easiest & one of the most beneficial being spkr placement.

There are other tweak things you can do like room treatments and isolation that can help but even with the best room, poorly matched gear will sound, well, poorly matched.

It's important to only do one change at a time so you can keep track of where you're headed in regards to improvements.

Part of the fun in this hobby, at least for me, is changing the system around from time to time. I've kept the same system together for 5+ yrs on a few occasions & other times change things once a month. It all depends on what you want to hear.

One last thing-on salesman. When you find one that will work with what u have, listening to what you're looking for & then making suggestions, which include home demo's, then you've found a salesman worth his weight in gold.