Mastersound 300b Compact-thoughts???


I am considering this amplifier and wondered if anyone as experience with it? Also, it seems from what I can read it is SS rectified, can anyone confirm this, or am I missing something?


Many thanks



I wanted to experience the 300b sound. So I got the Woo 300b amp for my headphone system. I also put in Takatsuki tubes in them. Honestly my headphone system became incredible sounding. So much so that I had a hard time listening to my $70K main system. The realism, natural musicality, detail… emotional draw. So, this caused me to completely upgrade and reconfigure my main system. Now both my main system have the same character, detail, midrange bloom, emotional connection. It is an all Audio Research Reference system… but you get the same warmth, natural sound, detail, musicality with the foundation series and even the integrated. 

Let me suggest, you are going at this in the most difficult way possible. Trying to power a main system with a 300b is a very difficult thing requiring lots of big compromises. You can get the character in a main system and with lots of power by using Audio Research, Conrad Johnson, Cary, or VAC. You can then choose from lots of great speakers.


If you must experience the best the 300b has to offer… get a headphone amp and power some great headphones. You can see my headphone system and main system under userID. A fantastic headphone system will cost 1/10th thst of a main system and you can get the magic of the tube through great high power components made to power the pajority of speakers on the market.

@mmcgill829 I'd say if your speaker maker recommends the amp they obviously have experience with it perhaps they can answer your questions? BTW what are your speakers?

@jond I'm having Coherent Audio 18s made currently, so investigating amp options that'll take advantage of their high efficiency (102dB). Frank recommended two amps - this one and a Tektron amp, but I'm not too fond of the build quality of the Tektrons (they look pretty thrown together for the price they ask). I'm sure they sound wonderful, but that's a huge turn off for me. Mastersound supposedly has excellent build quality, but I'm just hesitant since there isn't much info out there about these.

Some other short list considerations - triode lab 2a3 integrated, allnic T-1500 mk2, but that's for another thread to discuss 😂


I'm having Coherent Audio 18s made currently, so investigating amp options that'll take advantage of their high efficiency (102dB

In my opinion based upon what I have learned about the Coherent Audio speakers you’re going to be exceedingly happy!! You are on the right course with regard to pursuing lower power but high quality built tube amplifiers. Stick with your plans as your speakers will allow this to come to fruition.


Mastersound is a very reputable manufacturer that’s been around for years and I believe that they build their own very high quality transformers. My only concern is that 15 watts per channel rating is unusually high for the 300b tube. The good news for you is that there are no shortage of other low power SET (Or push-pull) tube amplifiers to consider. You are “not “ going about this in a wrong manner.

Frank has explicitly designed and implemented his speakers to be superb partners with these types of fantastic sounding amplifiers. Have you determined a particular budget range for your amplifier? Take your time and you’ll have a splendid high efficiency speaker/low power tube amplifier audio system. My system is posted on this site. I went this route 14 years ago and there’s been no looking back.


@charles1dad I've seen your system - looks great! I'm sure it sounds even better!

I'm mostly hanging around the 8-10k range all-in as far as pricing goes.

With some of the 300b amps like this mastersound, can find them gently used with low miles for around $5500, which leaves plenty of room to get some excellent tubes, but the power output concerns make it a bit of a risky endeavor. Even Frank switched to using this as one of his rotating amps fairly recently from what he said, so I'm not sure he will have a lot of insight into long term tube life with it.

The allnic can usually be found lightly used for around the same price point as well, and that is rated at 10 wpc output, which seems a little more in the normalish range.

Triode lab would be if I decide to go the 2a3 or 45 tube route instead. I've been eyeing the 2a3 in particular. They're beautiful amps and look very well made.

The tektron amp I was referred to does allow for tube rolling with 45, 2a3, 50, but again, just concerned with the build quality. Looking inside them, there's a lot of wiring and components that aren't supported by anything but their connections. It feels sloppy to me. I know they have a pretty good reputation as far as sound quality goes, but I just can't get over that. Even a reviewer had to re-attach things in their demo model that came lose in shipping (!), which for thousands of dollars just shouldn't be happening IMO.

Ideally looking at integrated amps since I don't have a pre-amp and it's questionable whether I would have enough room to setup mono blocks. I probably could, but it would be pretty tight.