What's the greatest bargain in SET these days?

Rebbi, Ignoring the huge difference in power, on the basis of sound quality alone, to my ears the dynamo was easily on a par with my Cary 500.1 MB amps which retail for about 9K. I do perceive a classic tube amp sound. There is midrange magic with the dynamo. Wonderful sophistication in the upper harmonics. In a double blind test, you would pick it out as a tube amp quickly.

The rectifier tube that came stock with my dynamo was junk. It began to arc with just a few hours. I had a spare NOS Mullard Blackburn GZ34 that I put in which is a great tube with this amp.

I really love this little amp. On the basis of sound quality alone, this is probably second only to my Coincident Frankensteins of all the amps I have ever owned. It is good with the stock tubes, but as Mikirob has pointed out, you are going to want to start tube rolling when you see what it is capable of.

Mine is still sitting idle until I get phase one of the move complete. I am doing all my listening with the Franks right now, but I am eager to get my dynamo up and running again.

Rebbi,
I totally agree with Brownsfan. I've got some good listening hours on the Dynamo now and I am truly blown away by how good it sounds, even with the stock tubes. The rectifier likely must be replaced; but you don't have to spend a lot of money to do that. Get a NOS Mullard 5AR4, if possible, but there are many rectifier tubes in the $40-60 range that will sound great. The Shuguang EL34s and 6SL7s that come stock with the Dynamo sound fine, but can be greatly improved upon. Tomorrow I have a pair of RFT Siemens EL34s coming, can't wait to hear them. I also have 6CA7 Black Treasure on the way, I haven't yet pulled the trigger on the SED Winged C. I was fortunate that I had a beautiful matched pair of 6SL7WGT-VT229 military in my tube stash. Between it and the NOS Mullard rectifier I purchased from Brent a Jesse it really upped the Dynamo's performance, even with the stock Shuguang EL34s. I love this amp so much I'm thinking of selling one of my other amps and purchasing another Dynamo; it will appreciate all the good ancillaries you can throw at it. You asked the question: What is the best SET bargain in all of audio? This is it!

What is it exactly that changing the rectifier tube improves?

Thanks.

Rebbi,
By this point there's been very good actual owner feedback and a "rave" 6 Moons review, pretty encouraging if you ask me.
1) Built by an established company.
2)The owener /builder has a reputation for developing excellent sounding components across the board.
3)1,300.00 USD brand new with a warranty.
4)very simple circuit, stereo chassis with only 6 tubes total!
5) Uses inexpensive tubes that are easily available.(very flexible tube rolling potential)
6)Uses good transformers(not a given in this price range).
7)Stout power supply (again not a given in this price range).
8) This amplifier has been reported as excellent with your specific speaker.
Just some food for thought.
Regards,
Charles,

A summary From Pro Guitar: What is a Rectifier?

What does a rectifier do? If you don’t know, don’t feel bad, you’re about to find out. A rectifier changes alternating current (AC), like a wall outlet, to direct current (DC) that is required to run all electronics inside your amplifier. That’s it, it’s really that simple. The AC voltage comes from the wall into the transformer of your amp where it is then run through the rectifier to get DC voltage. This is before all audio circuitry so an important thing to realize is that NO AUDIO SIGNAL PASSES THROUGH THE RECTIFIER. It is purely for voltage conversion. So how does it affect the tone if no audio passes through it?

Rectifier Types:

So now we know what the rectifier does. In audio, guitar and bass tube amplifiers, there are two different types of rectifiers you will see, solid state and tube. There are several commonly used tube rectifiers in amps, 5U4, 5AR4 (GZ34), 5Y3, and 6CA4 (EZ81). Each has different voltage handling and characteristics for different output levels and circuits but each accomplishes the same task in the circuit. That’s it, no magic, no mystery, purely a power issue.

A solid state rectifier is made up of two to four diodes in a circuit (generally, there are single diode rectifiers but they are somewhat uncommon in guitar amps) or an IC that is made up of diodes. The solid state rectifier, while being diodes and not tubes, accomplishes the same task as a tube rectifier, it is simply there to convert AC voltage to DC voltage.

Tone:

So if a rectifier does not pass audio, how can it affect the tone of an amplifier? Well, the rectifier is the first post-transformer link in the power supply and changing the power supply voltage will cause different tonal characteristics. Tube rectifiers have an internal resistance so the more current that is pulled through a tube rectifier, the more the voltage drops which in turn causes the output power of the amp to drop. This drop affects the rise time of the tube (the time taken to produce the proper voltage output) and as the note decays the voltage builds causing a compression like effect. This is commonly referred to as “sag”. Since low frequencies require more current to reproduce, this sag causes a tube rectified amp to have a spongier low end and distort easier. This natural compression and sustain is sought after by many guitarists of certain genres (blues, classic rock, country) but not for everyone. Many players feel that a tube rectified amp responds better to touch dynamics and sound warmer than the solid state counter-parts. Different types of rectifier tubes will have different tonal characteristics in the same circuit as well but, as with all tube substitutions, BE CAREFUL. Not all rectifier tubes are interchangeable so consult a qualified technician before substituting.