Beginner looking for guidance into tube sound.

OP, 
I built a system over the past year. I have Quicksilver and love it. It is extremely well made and beautiful sounding. I'm a huge fan.

But given the constraints you mentioned, I would push my own prejudice aside and affirm a couple other points made which I think take precedence.

First, the speakers are extraordinarily important, and if you were able to start building your system toward tubes, you should probably look for a bit more power than those used Quicksilver monos. But maybe not. I have 87db speakers with 60wpc monos and it's plenty of power.

Still, let's say you're ok with sticking with your speakers. What would make the most difference for $1-1.5k? I have to think it would be a good tube preamp or a tube DAC. Quicksilver and other tube preamps are possibilities; or Orchid MHDT Dac; or others. The point is that you want the tubes early in the signal path, first. Later, you can get tube amps. But before then, DAC or preamp. Gotta make sure the preamp and Peachtree will play nice together.

Did a little surfing with my coffee.

NEW

You could start with a tube preamp/amp integrated: https://heaven11audio.com/billie-stereo-intergrated-amplifier/

Or for preamps, there's still a new QS to go with: http://quicksilveraudio.com/products/line-stage-preamp/ or here for $1295: https://www.donwalkeraudio.com/quicksilver.html or John might do a deal for you: https://www.audioconnect.com/product/quicksilver-line-stage-preamplifier/

You might consider this maker, Erhard Audio. Here's his entry level: https://www.erhard-audio.com/Europa.html
Above this, for a few hundred more, there are nice units that include wood.

Used:

https://www.usaudiomart.com/details/649735683-conrad-johnson-classic-2se-tube-preamplifier/
https://www.usaudiomart.com/details/649657520-conrad-johnson-pv-12l/
https://www.audiogon.com/listings/lisaac7e-conrad-johnson-pv-14l-tube

https://www.usaudiomart.com/details/649733487-audio-research-tube-pre-amp-ls-2-black-markii-remote/
https://www.usaudiomart.com/details/649666817-canary-audio-c7/
https://www.usaudiomart.com/details/649710703-audible-illusions-l1-preamp-modified/

This one is especially attractive looking but I've not heard of Pear Audio before:
https://www.audiogon.com/listings/lisaabaf-pear-audio-blue-reference-preamplifier-tube

Aric audio, used for $900? This is a steal. I'd be on this like stink on a monkey.

Regarding matching, here's an email I got from Almarg, an expert and a gentleman. RIP.

On matching Preamp and Amp

Almarg:

"To assure impedance compatibility the 10x rule of thumb guideline should be applied at the audible frequency for which the output impedance of the component providing the signal is highest. In most cases impedances are specified at a mid-range frequency such as 1 kHz. It is very common for tube preamps to have output impedances at deep bass frequencies that are much higher than that specified value, often 2K or 3K or even 4K ohms. That rise at low frequencies results from the output coupling capacitor that is used in the majority of tube preamps, and also in a few solid state preamps. The impedance of a capacitor increases as frequency decreases.

So ideally the 10x rule of thumb guideline should usually be applied based on the output impedance at 20 Hz, in the case of a tube-based preamp. If as is often the case the component’s output impedance at 20 Hz is not known, and is not indicated in published measurements (such as those Stereophile often provides), and if the use of an output coupling capacitor in that component cannot be ruled out based on available information, to be safe a considerably higher ratio than 10x should be used, something like 50x or 75x IMO.

This applies, btw, to tube-based source components as well as to tube-based preamps.

Also, to clarify a common misconception I should add that failing to meet that guideline does not necessarily mean that there will be an impedance compatibility problem. It depends on how much **variation** there is in the output impedance over the frequency range. But meeting that guideline (at all audible frequencies) assures that there won’t be an impedance compatibility problem.

I should note also that a significant number of tube-based preamps use coupling transformers at their outputs, and therefore avoid that low frequency impedance rise. Although depending on the specific implementation transformer-coupled outputs might have downsides of their own. Atma-Sphere MP-1 and MP-3 preamps, btw, cleverly avoid the use of both capacitors and transformers at their outputs. (I’m not sure about the UV-1). As far as I am aware they are unique in that respect, among tube-based preamps.

Best regards,

-- Al"