Not that I know of. Its not about how powerful the amp is. doesnt matter actually. the adapter should be used on a tube amp because of the design of the amp. I was tried a tube amp around 35 Watts, but ended up not liking the sound as much, so I just went another route. it was easier for me. But anyway, the adapter protects your headphones on a tube amp.Anyway to hook a HE-6 to a tube amp & not worry about problems or sound degradation?
Even if the tube amp is in the 20 watt range.
Also, make sure you do the math to figure out if your getting the right Watts into Ohms ratio. on a 20 watt tube amp, your not likely getting the recommended ratio. most people dont think of this.