Ralph's (atmosphere) assessment is spot on as with some of the others.
Getting into High end anything seriously involves work. Some people fall into money, and really just want toys. Some enjoy certain things and really appreciate them.
Music is one of those things. Some listen only as background music (and there's nothing wrong with that for them), some like equipment only and the feeling of ownership of "high end" equipment. some really appreciate and enjoy the accurate reproduction/play back of music and want it to be as "real" and accurate as they can find and afford.
First I would recommend setting a price point for equipment. How is that done? Well, that is difficult. determine what sound you really like. accurate reproduction of vocals, musical instruments, etc. When you know that, go out and listen a lot to various equipment in different price ranges. since you aren't buying yet, don't limit yourself to certain price points. Listen to a wide range of equipment in various price points. Take your time. Go to friend's homes and listen, good stores that let you take your music and listen to various equipment. go to audio shows. But the point is to go and listen to a lot of stuff at various price points.
When you hear to sound and quality you like. Then you would have set the price point. If you are keeping your current speakers, then you have narrowed the field on amps. When you have done that, you also now know the field for pre-amps.
If then, you can bring equipment to your home and connect to your speakers, then you can get a realistic listening experience. it is really important to listen in your home on your stuff. if that isn't possible and you really want to keep your speakers, then ask if you can take your speakers to stores, and listen to amps connected to your speakers there. if they laugh loudly, then ask if they have similar speakers and listen there.
Just remember, when you are going to stores and listening, you aren't just listening to the amp/pre-amp. You are also listening to their speakers and cables and "their room".
If the store has a wide range of equipment that you are interested in (mostly this doesn't happen), then you can swap one amp for another (changing nothing else) and listen and get a good feel for that amp or pre-amp.
All of this take patience, learning and time. it can be fun and enjoyable if you aren't in a hurry and are patient. it is definitely not fun when in every store they look you up and down, to assess your spending capability, won't set up equipment for you, and are basically not helpful. Be extra careful of places that are trying to off load standing equipment.
But there are lots of really nice tubed equipment out there. There are also lots of really not nice tubed equipment out there. So, investigate, investigate, investigate, listen, read, ask, and most importantly take stuff home to listen there.
enjoy