What will a preamp do for me?

Short answer, yes I am daisy chaining three preamps at this very moment.Debussy in the five disc changer I paid $40 for on eBay$125 Toslink (Lifatech) from that to my $7,000 fancy DAC (or SACD player, your choice but you ask why not just use the spinner in the $7K wonder??? ahhh lazy, five beats one for lazy) The Balanced out goes direct to Bryston BP-26 when I want that. the single ended to the recently bought Threshold FET10 linestage, and from there it can either go to the BP-26, or to my Conrad Johnson ACT2 which in turn feeds another input to the BP-26.                                          
So at the flip of the selector on the Bryston I can hear direct via XLR (Cable is Cardas Parsec) from Marantz SA-10, single ended )able is Kimber KS1016) SA-10 from the Threshold, or single ended SA-10 from the Conrad Johnson via the Threshold(with a Cardas Parsec TO the Conrad Johnson, and a Kimber KS1016 to the BP-26). Direct XLR is the tightest, clearest, alas slightly boring. From the Threshold, more body, more bass and alas, slightly ’dry’(but actually real good). From the Conrad Johnson, ahah! That old second hamonic kicks in... Just right. (everything else stays on 24/7. Sadly the Conrad Johnson ACT2 is blast furnace hot for a preamp gizmo, and only on when used, and yes that is it’s normal state. Curiously the Threshold is stone cold when left on/in use, so is it’s power supply)The difference between choices one two and three is very very tiny. But hey my ears, my money, my choice.
And I LIKE preamps... I own several more... An Audio Research Sp-15 an Audio Illusions Modulus 3A, and a Onkyo Grand Integra P308. Plus the not working VAC Standard in the closet.

Well, I am not going to chain together three pre-amps, at least not any time soon, but I do appreciate all the ideas! 

elizabeth - I read with interest your thread titled "how do you know which component to upgrade" and found it very insightful, except for the fact that it ultimately didn't answer my question, not that I really expected it to :).  But I am happily following your advice so far, as left for me on a similar post, kind of a false start to this one.

atmasphere - I am dedicated to keeping all things balanced.

mrdecibel - 85% of my listening, and nearly all of my critical listening, is a mix of Americana (Tidal's nomenclature, aka folk, alt-country, chamber pop, laurel canyon pop, jazz pop, non pop radio pop, alt/indy, some but not all rock-n-roll, etc) as well as jazz and classical, generally at 75-85 dBs.  To my inexperienced ears, my system sounds pretty darn good for this type of music in my room.  It just bugs me that when I want to rock out, the sound is not as enjoyable.  Ditto the treble.  

gosta - I love the Theils - for now.  Speaker upgrade is well out over the horizon, but certainly out there, albeit way out in the future (2020 maybe?).  My goal for now is to make the 2.3s sound as good as possible, maybe even upgrade the crossovers, before moving on.

all - sounds like there possibilities both ways, my conclusion so far is that ultimately what I am looking for COULD be achieved without a preamp, AND it's also likely that the RIGHT pre would also make me very happy. If the right pre is right to me because it colors the sound a certain way, perhaps I can get there following another path?

So far I have improved isolation of the amp (moderate improvement) and plugged it right into the wall outlet (also a moderate improvement).  Next up is a Furutech wall outlet (Rhodium plating, "Rhodium especially excels in the high frequencies which are detailed and clear. Overall rhodium yields a super responsive, delicate, expressive and neutral sound…" - we'll see.  Then I think I will try some NOS 6SN7s, old Russian tubes from Upscale, in place of the current Sylvania Chrome Domes.  Upgrading the source to a PS Audio DSD is the next big component improvement.  After that, speaker isolation? And then, maybe, the Schitt Freya, because it is balanced, gives me three modes of operation to play with including passive, (four if you count the Octal LISST option) but even more importantly, it can be returned (it will be a tough 15 days of burn-in and listening, but if I plan ahead, I think I am up to the task).  And of course, room treatment will continue.  Or maybe I will come across what could be the perfect pre-amp at a price that not buying would be very regretful, who knows, it could happen! 

More advice is welcome!  

Just discovered.
Elac Alchemy DDP-1. From their new digital serie. May be of interest.
Combine with streamer DMP-1. Has AES output which could be led
directly to pro monitors with digital input. Becoming rather common.

Basically a preamp will make whatever a DAC does, but better. A preamp is a must have item in any hi end system. I was not enjoying my system and messing around so many things trying not to expend money on a preamp. I was partially convinced to buy a preamp. I did then bought a used hi end one. That was amazing. That was the best improvement I did I my system. Sounds were then clearer, better played. I think it is a good improvement you can do for your system. Today, if I had to start a new system, that would be my first bought. That is the brain of your system. The amp is the heart and the speakers are the legs.

There's talk of not using a pre-amp because you don't need an extra gain stage. Hate to break it to ya, but a pre-amp gain stage is generally a better gain stage than a power amp gain stage. You can better optimize the power supply and it's an electrically quieter and easier environment to manage since you're not piping huge currents all over the place. It makes better sense to use an amp with as little gain as you can get away with and get as much voltage gain out of the pre-amp as you can. That is a valid approach some people take. With enough voltage gain in the pre-amp all you need is an impedance converting power amp with zero gain just to provide the current to drive a load. It's a good way to shield your voltage gain stage from the ugly world of reactive loads.