Speaker for 300b amp?

You have some good recommendations above.  I have two 300B amps, both running WE tubes, and have been playing around with speaker combinations with my Cary integrated amp for 15 years.  I like horns but recently discovered Omega Audio speakers made in Connecticut by Louis Chochos.  I was having trouble finding a good fit for my Tool Shed Transcendence (8 wpc) in a smaller room (14’x15’) and his Super Alnico Monitor really did the trick.  These speakers have no crossover which was new for me but the range on his drivers is unbelievable for a stand mount speaker.  He’s easy to talk to – I recommend calling him and having a conversation regarding your setup and needs.   He also has floor standers if bookshelves aren’t your cup of tea.

The other speakers that I’m in love with are my Volti Rivals which I have in a bigger room.    These horn-based speakers are made by Greg Roberts in Tennessee.  Like Louis, Greg is easy to talk to.  I visited his shop when I traded him my 40 year old Klipsch Belles.  Spent the night listening to all sorts of music with him and then camped out overnight in his veneer room.  Six weeks later I was picking up a beautiful pair of Red Gum veneer Rivals.  His line of speakers are quite a bit more expensive then the Omegas but boy do they play... like you’re in a live music setting...and they resolve.  If you are looking at any of the Klipsch Heritage line you really need to speak with Greg and schedule a demo.   His YouTube videos are a hoot.

The other option I might recommend is finding an older pair of Klipsch Heresy’s, Cornwall’s, or Lascala’s and doing a little crossover and driver updating.   Greg sells DIY kits for the LaScala’s, Belle’s and KHorn and I think he may even take on an upgrade project himself if you can convince him to re-veneer the cabinets.  I have 2 pairs of Heresy’s (1&II) that I’ve worked over myself (Crites parts) and they sound great with my Cary 300B integrated (15 wpc).  I put them on stands to get them off the floor which I think improves their imaging.

Hope this helps just a little bit.  Good luck and happy hunting!

Check out the ampsandsound website.  If you see something interesting (or even if you don’t) give Justin  (the Owner) a call.  He usually answers the phone and can be very helpful on the subject of 300b amps and matching speakers.

OP 

I have heard the Reference 3S deCapo powered by a pair of Mono 300B

it sounds sublime, very musical and it truly engages emotion. the DeCappo do not have a Crossover and only uses a single Cap on the HF Driver. It is a stand mount speaker, if you are looking into this size

Larger speakers are best served by Pure Audio Project (PAP) which i also have heard. The DeCappo , for me, needed a well-integrated Sub to fill in, while the PAP can be stand alone. Your choice

Btw, I also like Zu speakers and Ryan Casey @Marlin38.  I had a pair of Dirty Weekends for 4 years during COVID and they really performed well with the Cary 300B. I always thought they punched way above there price level but unfortunately sold them to make room for Clayton Shaw's Caladan's which also played well with the Cary but was not a great fit for my smaller room.  Harbeth HL5XDs followed the Caladan's but too much bass bloat for the room and not efficient enough for the Tool Shed amp.  As stated in the above post my search for that room has ended with the Omega's. 

mikewarner

You did not mention price range

Volti or Fyne - Both brilliantly made, very high sensitivity, and sound great with low wattage amps with some current behind them

Volti Luceras are 99db efficient, and the Razz are 100db

Fyne Vintage classic line is around 95 db, the Vintage Gold line is 96/97db, and the Vintage are 96/97 db. The price