Bench tested truth
I tried this and another brand of "portable mini amp." This one actually bench tests at a true 44+ watts of output RMS into 8 ohms. (actually mine tested at slightly higher 48 watts, but that was with a regulated AC power supply to feed the included power-supply.)
The included wall-wart that comes with these is FAR better than most. It is HEAVY duty. That's important since any amp can only be as good as its power supply. A good power-supply does not guarantee a great amp, but a crummy power supply DOES guarantee a poor performer. This power supply also has sufficient cable between the transformer and the amp to prevent inducted EMI noise. Obviously you must not wrap power cables around signal cables for any amplifier. If you did not already know that, consider yourself so informed now. Ask any "sales Engineer" at Sweetwater if you don't understand. They are all trained to know that stuff and explain it.
With high-output pickups, you can plug straight into this and get superb old-school clean tones that smoothly grade into saturated distortion just like real tube amps. That means you can use your guitar's volume knobs like a real musician.
It does NOT go into stuper-gain metal madness without a pedal in front of it, and that's a good thing. With the bright switch ON and gain near max, it sounds AND behaves very much like a 18 watt Marshall or old-school plexi, just quieter.
The sensitivity of your speakers has far more to do with perceived volume and tone than this amp does. Since I am a speaker-geek, I tried it with a wide variety of speakers including 8", 10", 12" and even 15" bass speakers. My extensive speaker collection includes classic Celestions, Eminence, B&C, selenium, peavey, Faital, Dayton Pro and others. The amp drives all of them well and you can actually hear the tone of your speaker and cabs. That indicates the AMP is neutral and cooperates with gear you already have. Just be sure to have the appropriate CABLE so you can connect this amp to your cabs.
At moderate gain, It has a tube-like saturation and "sponginess" that feels very much like a modified tweed class A amp.
With the gain at 12 o'clock and single-coil pickups, bright switch engaged, it is very clean and "strat-blues" sounding.
With the gain above 12 and hot humbuckers, bright switch off, it can go from clean jazzy tones to smooth distorted leads without shrillness.
The input stage is designed to handle a WIDE range of input voltages, so it is very "pedal friendly." I tested it with aCarl Martin Plexi-Drive, a Sansamp GT2, a ZOOM multi effects, a classic tube screamer and a Boss overdrive. All those worked admirably well and the amp allowed their unique characters to shine through. Depending on the preamp or pedals you use in front of it, you must adapt the volume (gain) to match the characteristics of that particular pedal.
Bench-tested Signal-to-noise is better than most guitar amps at <91 dB. Obviously, when the bright switch is engaged, you hear more hiss since that switch is a simple treble-cut. Judging by the capacitor value and sound, I'd guess that switch cuts treble above 7 to 10 kHz. When ON, the bright switch sounds like a presence control of real tube amps. In noisy nightclubs, you need the extra high-end to get articulation above chattering patrons. But you won't notice that hiss above the din. In quiet environments, you might want the bright switch off, especially if you have sensitive ears or dislike clean articulation in favor of muddy grease to disguise less than perfect technique.
I am surprised no other reviewer so far has mentioned what a great amp this is for blues harmonica! Because of its input range, a classic bullet mic sounds incredible through these amps! Think of Sugar Blue and the harp solo on Zeppelin's "When the Levee Breaks." I piped this through two 8-inch speakers in a closed cab using the Shure Green Bullet, gain on max, bright switch OFF. Almost made me want to start a blues band! ( except as a Jazz player, I'm already poor enough.)
Kudos to EHX for honest power ratings and rugged design.
My only criticism would be the large heavy wall-wart power supply, but that is a necessary compromise to skirt UL certification hassles and keep cost low.
Thanks to Brian Lemert for letting me try both mini amps before selecting this one. He tolerates my technical questions and persnickety tone snobbishness.
As a spare amp for emergencies that fits in your glove compartment, I can find no better amp or value. For a guy who likes to travel light and already has a nice assortment of pedals, this thing is awesome. I would feel perfectly comfortable using it as my main amp and so far it shows no sign of failure. Highly recommended.