Old or new gear

Pick your amp and then pick your pre, or vice versa. Impedence matching matters. Thats why you may read that someone has a dac with a volume control that works perfectly feeding their amps direct sans pre, while others proclaim their system collapsed. They got lucky that the dac matched up well in the volume range they listen with the amps they chose. There is alot of data out there but it adds another layer of complexity to chase down in the event you are not thrilled.

@sophie999, I think your inquiry about Quicksilver monos is a great place to begin, and end...

I just sold my pair, as I'm moving to a house half the size of my current one.  Both love and respect the build and sonics of the Quicksilvers, along with the fact they're made in America.  You can't go wrong with them, as they have an incredibly simple (Dynaco), hardwired circuit.  Outside of blowing a transformer, no matter what ever goes wrong with them, you can easily source replacement parts, and either make the repair yourself or have a tech do so.

I also second the Dynaco suggestion from @roberjerman.  Obviously, what I said about Quicksilver holds true for Dynaco.  Given the company produced several hundred thousand amplifier kits, the vast majority assembled by folks with zero electronic assembly experience, it seems easy to say Dynaco produced the most reliable high-end audio components of all time.  Most underrate how good they actually sound, however.  And in my opinion, having heard most of the modifications that "fix the design flaws", I believe the original sounds (and works) best.

In my opinion, a simple tube design, whether SET / PSE or push-pull, employing hardwired construction represents the best long-term purchase when it comes to amplification.  Such products mean you'll likely never get stuck someday owing a mega priced doorstop.

For what it's worth, I previously served as the North American importer for Opera Audio / Consonance.  The company builds a staggering array of products, including tube amplifiers, specifically.  Some of the tube amplifiers sound really good.  If I would recommend anything they produce, they would lead that list.  That said, many had the sort of implementation and reliability issues that go with 1) building so many products that none receive the level of attention in terms of design, implementation, support, and iterative improvement as a company dedicated to building tube amplification alone, and 2) the gap between the owner / designer of the company and the folks actually building the product.  Given most employ printed circuit board construction, over the long term, I would have reliability concerns not present in the aforementioned two products

If you decide to get the QS amps you can get the QS preamp to go with it!
http://quicksilveraudio.com/products/line-stage-preamp/

Another plus for Quicksilver, i believe Mike Sanders has just about perfected the art and science behind tube transformer design. Great amplifier lineup from bottom to top. I have a pair of Silver 88s and i just love these amps. With the right speakers they are about as ideal as it gets. Check out the 20 watt integrated at 1995.00, wonderful with the right speaker. I heard with a pair of 12k ref 3a Reflectors, very impressive with those monitors that hide nothing. That integrated helped them totally disappear.

Thanks. 
I think I will go with QS mid monos based on my research and multiple comments here. Will schiit saga pre match with it? That's a $650 price difference from QS pre. Seems to have output impedance 180 ohm vs 100 for QS. Also no output gain for saga. Is QS really worth extra $650?