Is a 50-watt amp too loud?
Recently, I've watched a number of conversations about sub-20 watt amps being the "new" amp of choice for modern venues. The 100-watt monsters of the past are clearly overkill, and even 50-watt amps are too much. Or so "they" say... I say that there are no hard-and-fast rules. Proper amp size depends upon player, guitar, amp design, and number and type of speakers.
Let's take, for example, a Vibro-King. Don't be put off by the notion that this is a 60 watt amp. It works well in smaller venues. First of all, the VK is rated at 60 watts into 2 ohms. The actual load presented by the three internal speakers is 2.7 ohms - the mismatch will cut the delivered power slightly.
Second, the Jensen P10Rs have a low efficiency - about 94 dB/W @ 1 M. Most guitar speakers are 3 dB to 6dB more efficient than these. So you should really compare a VK to a 15W or 30W amp, depending upon the speakers in the other amp.
Next, the VK's architecture is a bit different from every other Fender amp, as far as I've been able to tell. It's most similar to a narrow-panel Bassman (5F6 or 5F6-A), but the tone stack is classic Blackface instead of the variant that Jim Marshall perpetuated in his amps. What this means is that you can turn all the tone controls to near zero and cut the volume way down (just like in a Blackface amp). But... the volume control is after the first gain stage and the the tone controls are after the second, so you can crank the volume and cut the tones to get some preamp distortion at low volumes. Or you can use this to get the preamp and power stage distorting at about the same time.
Finally, the VK has no negative feedback, so there is less clean headroom than in a typical 2x6L6 amp.
Long story short, the VK is a great blues amp - even for small venues. For performance, try setting everything at 4 (with fat control "on") to start with, then adjust to taste. If you want to increase the clean headroom, lower the volume, turn off the fat switch, and crank the tone controls.
For low-volume (conversational level) playing, a compressor in front of the amp helps to fatten up the sound. At performance levels, though, the amp and speaker compression is perfect. I may yet get a Hot Plate to adjust (not control) stage volume. I can already get great tone at acceptable volumes for small venues, but being able to push the amp by another 4db or 8db can change the playing feel.