Tube amps and low impedances

I wouldn't recommend using a tube amp for speakers that dip to 1 or 2 ohms. That is enough of a struggle for a well built SS amp. A speaker with a nominal impedence of 4 ohms, with a dip down to about 3 ohms is about as much as you can expect from a tube amp.

Most tube amps have impedance matching output transformers built into them. You have to select the most appropriate impedance tap for your speakers and it "should" produce rated power into that load. Having said that, there aren't any speakers that i know of that maintain a steady state non-reactive load that is of a consistent impedance. As such, the output transformer is somewhat of a buffer, but power output WILL vary even with it in place.

As a side note, many tube based amps do fall off in power as impedances are dropped, especially at the very low impedances that you mention. If i was going to run a pair of VERY low impedance speakers with a tube amp, i would probably look into the Mesa product line. Since they build / design professional tube based amps, they know how to compensate for very low impedance loads. Whether or not you like the sound that their circuitry produces is a personal thing, but at least you wouldn't really have to worry about straining / blowing up the amp or tubes all the time. Sean
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With impedances that low....would biamping with a SS amp on the bottom and tubes on top relieve the tube amp of the strain?

Totally opposite:

Tube amps drop their output power as the impedance goes down and capable only to drive a high impedance loads opposed to the SS amps that have a large current delivery capabilities certainly depending on output stage configuration and power supply.

An output transformer for the tube amps is an interface to match impedances of speaker with output stage that in real case requires the impedance to be much higher than even 16 Ohms.
Tube output stages have no current delivery possibilities and mainly amplify the voltage. Thus with transformer output stages tube amps deliver same power to the different load values depending on output transformer capabilities to handle the low impedance loads for certain time.

For what ever it's worth, as I have absolutley no experiences with them, the tubed Walcotts are supposed to be able to handle low impedances. Some respected Audiogoners have praised them.