Tube Amp, Preamp upgrades -- what did you do that improved your units?

@jjss49 9

(a) I am committed to keeping this gear.

(b) I would look to a local tech, highly recommended. I wouldn't trust myself to do it anymore than I would trust myself to pick out carpeting on my wife's behalf!

Agree about the ship/ship cost and risk concern.

Good point about the re-sale; Tvad was saying that earlier. My sense is that this unit has really, really good fundamentals and I'd likely be nipping an upgrade bug early if I just take it to a better level, now. Judgement call. I'd rather experiment with speakers and Dacs, etc., down the road, knowing that my tube gear was batting .450

Violating the warranty is a concern, but there's only a little bit more than a year left on it. I could wait, but a caps change seems low risk. I suppose I'm tired of being risk-averse. Could it be the age we live in?

I hear you about the conservatism — I think we're alike. A couple of things are swinging me in this direction:

* Experienced opinion: QS owners who have done these mods are unequivocal in praising the results
* Reality check: This QS gear is not on the level of, say, others — Atmasphere; lots of room to improve; a quick look at some of the parts costs quickly confirms
* Plan B: My solid state can carry me pretty well, if necessary (assuming my preamp is ok)
* Settling the issue: I think it's in my head to do this and I have the time to enjoy the process right now.

All your caveats make a lot of sense — thank you for writing them out.

Sometimes I approach these questions as if they were serious medical procedures; they're not! This is a hobby and I'm trying to slide into the greater ease I see in other hobbyists with, well, trying sh*t!

@grannyring Yes on the .27uf combo from Audience or Sonicap. Both should be a step up. I am basing this on the parts quality used throughout the amp which are modest. Someone is making the QS caps, but I am fairly certain they are not quite up to the Audience XO level of quality. 
Yes on the 47uf preamp caps. I added the bypass idea which is a no brainer and will yield sonic improvement. Look up the dimensions of this Mundorf cap and be sure they will fit. Just make sure. I bet they do, but……

Yes, agree. Modest at best on the stock caps in the amps and preamp. Studying a bit inside, maybe Solen or Sonicap ? is OEM with the odd .27uf on the amp IT side and 2.0uf in the preamp. The mfg owner-designer shared he likes aluminum foil caps. There are four $4 715P Orange Drops in these amps on the OT side. Replaced those on mine after year one, along with a five+ others who followed here on A'gon. Yep, a no-brainer.  I was astonished at the results, making the simple cap upgrades for these very solid amps which already have good bones. 

grannyring has good advice above.  I like the VCap Odams much.  They are also easy to work with size wise. But you'll need to tell your tech that their bodies are somewhat conductive. I wrap them in silicone tape prior to install.    I would simply start with the coupling caps and output caps (typically located right before the lines running to RCA outputs).   If it's a preamp you are upgrading, you can match your output cap better to your amp if they are of different brands.  There's a nice calculator on the VCap website for this purpose. 

I was never able to find a tech that wanted to assist with modifications.  It's kind of like taking your car to a service place and asking them to install specialty muffler, brakes, etc.  They typically aren't jazzed to do it and they look at the vehicle as if it were an appliance--not to be touched from the engineer's design. 

I've experienced far more meaningful results upgrading caps/resistors than I have playing with hookup cables/power cords (I do that too but I just hear more of an improvement from the other stuff).  

One warning you didn't get yet---It's slightly addictive.  I spent $900 upgrading my crossovers on my loudspeakers.  I bought Cornwall IVs but would have loved Volti speakers (didn't want to spend $10k).  The crossover upgrade got me where I wanted to be.  

Modifications can keep me from upgrading by allowing me to get more out of a design I already love.  A Ford Mustang or even Chevrolet Corvette are built to a price point--they are not a Rolls Royce. So there's a good foundation to make improvements to your specialized taste.  Enjoy your journey!

@jbhiller

I would simply start with the coupling caps and output caps (typically located right before the lines running to RCA outputs). If it’s a preamp you are upgrading, you can match your output cap better to your amp if they are of different brands. There’s a nice calculator on the VCap website for this purpose.

Thanks for weighing in. Help me understand -- you say the "output caps" are "typically located right before the lines running to RCA outputs." My amp only has RCA inputs. I’m looking at a picture of the inside (at my system page, hilde45 ) and I’m trying to determine which caps you mean.

As for the preamp caps, I AM intending to modify BOTH the preamp and the amp. Your advice helps me because I’m leaning toward Mundorf for the amp and then could do VCAPs on the preamp.

I would not use Mundorf film caps for your amps. They are rather tipped up in the upper midrange and can sound a tad too brilliant and artificial. This is compared to the better sounding caps like Vcap Odam, Jupiter copper foil, Jupiter HT and others. These other caps are more coherent top to bottom. I am referring to the Supreme silver/oil and silver/gold/oil caps. I am not referring to their line of electrolytic capacitors.
My experience after using them several years ago.
If you are looking for some tipped up energy in the brilliance area, then the Mundorfs may be a good choice.

The  film caps I pointed earlier are all coupling David. The 2.0 uf white caps in your preamp are output caps sometimes called output coupling. You can use the Odam 2.2 uf there. In this output position 2.2uf is perfectly fine. This position is not the same as the stage coupling caps we discussed not changing the value of.