Where should the Tubes Go in a Vintage Preamp / Amp System

Everything has already been procured and installed (almost), so I am probably not going to change anything out - at least not at this point in time.

My speaker choice might be a little controversial, especially to those unfamiliar with my final choice. At one time I had 17 different sets of speakers in my listening room (including names like Vandersteen and Bertagni, JBL and Ohm) ; over a couple of years time I narrowed down to my 2 favorites. I have a pair of fully restored 1971 Klipsch Cornwalls, and a pair of fully restored (and slightly modified) 1970 Sansui SP-5500s... And I am 98% sure that ultimately I am going to go with the Sui's...

The Corns are wonderful: they have been completely restored, with recapped crossovers, refinished cabinets, all new hardware and new diaphragms on all the horns. They have a great frequency response and of course, that famous Klipsch sound. I added removeable grilles (OEM in '71 the grille fabric was stapled to the front board) and I painstakingly refinished them in a deep walnut myself.

The SP-5500s are so different then what most people think of when they hear 'vintage Sansui speakers' that there is almost no comparison to anything else Sansui ever made. The cabinets themselves are a full inch of true MDF on a plywood frame and each speaker weighs over 105 pounds. The 15" woofer has a 9 pound magnet, a solid brass bobbin and weighs 17.5 pounds. The single midrange horn is made from tig-welded aluminum, is 17" wide X 6" tall and is simply magnificent. The twin horn tweeters were co-developed with JBL and are blissfully subtle yet detailed. There are (2) 4" lower midrange (midbass) cones, which I removed from the circuitry as I felt the combination of the massive woofer and that mid horn covered that portion of the sound profile well enough - and eliminating the response of those cones also removes any overlap and some of that "Kabuki" -ish ness that plagues many Japanese speakers of the era.

I'm sure there are some out there who are thinking "Sansui speakers, seriously??!!"... you need to trust me when I say that most people, even those in the audio community, have never seen or heard these particular speakers. They are quite rare, and were quite expensive when new - MSRP in 1970 was $900 / pair (that's almost $7K in todays dollars). They were never sold in the US market, so finding them here can be a chore.

The SP-5500s are also fairly efficient (98db) and pretty to look at, with genuine maple veneer and a hand carved rosewood grille.

DO NOT confuse these with something called the SP-5500X - which was indeed 'Kabuki crap'.

Anyway, interested to know what a better choice for a tube preamp would be. I am so far happy with the Dynaco but I am always open to suggestions.

Pretty sure I am going to stick with the Mac amps, though. 210 wpc and (IMO anyway) very good quality. The main caps have been replaced, along with a couple of resistors and output transistors. I feel like they handle my musical tastes quite well;  mainly classic rock and pop, but I also enjoy most other genres from outright classical to jazz and even the occasional (old time) country and folk music.

Any perticular reason the Dynaco preamp? Not what i would call a great pramp and the tube types are getting harder to find. If you have it already fine it will do but it will be the week link in your system. 

As for tubes and where, preamp first and power amp second. Power tubes are much more expencive then preamp tubes and do not last nearly as long. I would always go a tube preamp and SS amp over a SS preamp and tube amp. If you have efficent speakers maybe a tube amp as well. I'm not a fan of big power tube amps they seem to lose something as they get more powerful. 

I was in the same quandary when I was starting out. I went with tube preamp and solid state power amp. This was great for a few years until I tried a tube power amp. I’ve been all tube since—now using rebuilt vintage tube monoblocs.

There is no single good answer other than the devil is in the details in each case. 

I agree with @viridian 

If your speakers are 91db efficient or above  a 45-60 wpc tube amp will work. fine. I have 93.5 db efficient speakers and ran them fine with 35 wpc VTA Dynaco ST 70. I've had high power amps and low powered amps. Low powered amps sound much netter IME. I might even say to look at VTA   ST 70 / ST 120  amp 

I prefer high power amps, and don't want to deal with a high power tube amp, so using Class A mono blocks and tube preamp...I've often used tube pre and ss power amp to good results...from friend's systems both ways can work great...

My experience is completely practical, not theoretical so YMMV. If, and it is a big if, you can find speakers that are synergistic with the tube amp, a ss preamp and a tube amp will always yeild a sound most like tubes. And as a bonus, the combo often has less ambient noise. Not always though.

But there are several concerns, power output tubes are, generally, more expensive and have a shorter life span than small signal tubes, and all tube amps are in search of a sympathetic load. Good luck and happy holidays.