Tube amp forethought

good time to try tube power. many products now self bias and new production tubes are cheap, abundant and very high quality. I don't know if those speakers are candidates for tube amplification but others will chime in. you will get lifelike tone, imaging and sound staging from a good tube rig. I own a PrimaLuna and have been using tube amps for decades. This is the best I've owned in terms of reliability, value and most importantly sonics.

Look for a used Bedini 25/25 for your Quad ESL 57 speakers. One of the best matches.

Check out the Audio Research Documents page. They have biasing instructions for most all their classic amps. Usually, although there are exceptions, all you need is a small insulated screwdriver, a meter that can read millivolts and the restraint to keep one hand in your pocket when the amp is live. For the most part biasing is setting the standing current for the output tubes by measuring the voltage across two points while adjusting a pot with the screwdriver.

Usually you bias after the initial tube install and then after an hour or so of warmup. The manufacturer will have recommended bias values. Run it for a week or two and repeat. After that you should be good checking it every few months. You see a deviation your not comfortable with its time to look into new tubes.

Self biasing is for people who'd buy a self driving sports car. I get the convenience and all but why even bother when you can get a mini van.

Nothing against people who like mini vans or have to have one. You're just looking to get from A to B with minimum fuss. I guess like self biasing. Just not as involving to me.

@jperry +1 - I used a Bedini 25/25 with my Quad 57's for years. The only tube amps I found comparable were the Futterman OTL's (I still have 3). An alternative choice would be a nicely restored Quad 303. The 57's are voltage-limited. They will be damaged with more than 20 volts (50 watts).