EPOS ELS 3 with SET Amp?

If you want small moniter size speakers, to be driven by a SET amp you would be much better off and happier with single driver speakers. Check out Tekton, Fritzspeakers, Omega, ect. Truth is, most two-way monitors such as the Epos don't really perform well with low watt tube amps.

I doubt the music will have any life to it. With the 4 ohm impedence, I would imagine the music will not have much drive. The vocals might sound very good but the frequency extremes would be missing in action. Epos speakers have a rep of needing plenty of current drive to bring them to life. I would stick with an 8ohm or higher speaker with a sens of at least 90db/1w/m. I have found you can cheat on the sens if you use a speaker with no or a very simple crossover. This protects against any funny business in the impedence trace. This will make your 300b very happy.