Pre and Amp Suggestions

Given the way these things go, I’m almost afraid to ask this question but here goes: I’m finally at a place where my front-end and speakers are at “destination” level-at least for me....for now.  My question is where and what to upgrade between these two extremes. The speakers in question are Revel Studio 2s which I love, and the front-end dac/streamer is the Lumin T1 ruining Roon. The Lumin feeds into an analogue bypass section (no digital conversion) of an Anthem AVM60 going in turn to two 200 watt mono channels of a Sherbourn 7300. In trying to answer my question, I would appreciate keeping to the following parameters:

-no suggestions of other speakers or front end gear, I’m in a good place where I am right now.
-no suggestions of power conditioners, cables etc. Let’s just stick to the gear.

Just looking for pre and amp recommendations (or really good SS integrated amps). The sound right now is quite neutral, but perhaps a little lean but very revealing. I’m not looking to drastically alter the sound or play louder, just looking for more of the “good stuff”, resolution, staging etc. Might consider a tube pre or hybrid but really have no interest in an all tube power amp or massive class A space heater anymore. Ok let the games begin!
I already had the hotel RB-1590 amp and finally found a reasonable deal on an RC-1590 preamp, which replaced my RC-1580. I was going to go to vinyl, for which the 1580 was designed. But, I decided to go all digital instead. With the 1590 pre/amp combination, the separation and soundstage are very good to my ears. Some have said that the RC-1590 sounds a "a little thin." I am not sure I would disagree. But, if it does sound thin, it is only very little so. On the other hand, this combination is one of the few I have had that I can listen to for many hours without feeling fatigue. The dynamics are very good. I have had combinations with the RB-1590 that sounded more dynamic. But, I could not stand them for more than about 30 minutes. So far, especially for the money I could afford, I am very pleased indeed with this combination. I no longer feel that my preamp is the limiting factor in SQ. I have some XLR cables coming, and I expect them to give me "thicker" sound. But, even if they don’t, I don’t feel the need for more. It sounds as good or better than most systems I have heard at quality shops, with less fatigue. Once you get to a certain level of SQ, the benefit/cost ratio seems to get smaller and smaller.
Well, here I am circling back here a year later. The Vitus is great but I think I still need to consider either/and a tube front end or class A amp. I think the pre section of the Vitus may be its Achilles heel so to speak (and it is by no means bad) and I can run this as an amp only so a tube pre is possible and likely cheaper route. I never warmed up to the 6H30 tubes in my arc LS25mk2 but I am considering one of the older BAT, ARC Ref3 or similar which would run a 6922 or 12ax type tube. Any suggestions? Budget around $3-5k used.
The 6H30 is based on the 6922 in many ways- they are both frame-grid triodes, and IME have a similar microphonic 'iridescence'. If you really want to hear a good tube for a line section in a preamp, look for a preamp using a 6SN7. Unlike the 6922 and 6H30, the 6SN7 is actually intended for audio. One of the advantages of this is its a lot easier to find one that isn't microphonic.
@spinaker01  - FWIW as I stated a few months ago after getting the Pass mono's going I too was on a pre hunt and ended up with an Atma-sphere MP3. 

I had tried an MP1 in my rig, which was out of my budget, but the MP3 has much of the MP1's awesomeness and after that it was pretty much a no-brainer.

After some tube rolling, things have settled in nicely and at this point not really sure how much more I can improve things (within a normal sanity level).  Anyway just something to consider.

6SN7 tubes have a really nice sound. There are a few choices there. The fanciest on in your used price point would be Cary Audio SLP-05 Preamplifier. Beautiful 2 chassis design that has balanced XLR to amp.