Ok, a contrary opinion from a contrarian.
I have not heard a 46 amp, but own and LOVE a 45 capable amp - which should have around the same 1.5w of output power. I use it on 100db sensitive Altec 604s and even rely on separate powered helper woofers for the low bass, so when all put in a normal sized listening room of 13 x 21, think I'm giving that little amp as good a chance as I can to do it's thing - short of using even more efficient all horn speakers that just aren't appropriate for my small room (IMO).
With some switch selectable internal changes, that same 45 amp can use 2A3s (3w?), and I've been through many 300B (6w?) amps, so have 100's of hours of comparison in between these 3 approaches, or at least the implementations of them I've had in my system. Lots of time to draw conclusions and almost all of these amps have sounded 'good', so it's been a joy trying to decide which best suits me.
And "me" is the key; this is SO personal with so many variables like speakers (!!!), room, musical preferences, usual listening level, etc. that only you can make the call if 1.5w is enough.
The 45 is my all time favourite tube so far, especially with Jazz, some Americana and Blues. With the right recording; mesmerising presence, flesh and blood in the room, real full-scale instruments playing in interesting acoustic spaces that erase the room walls - the "psychedelic...pink cloud" Guf speaks of. On a regular basis, I'll flip the amp, set it for 45s and pop in my favourite pair (RCA globe 245) to get lost for a while. I love what this tube can do.
But for me, 1.5w is not enough.
My musical tastes are all over the place, and eventually I'll want to listen to something that makes the little 45s sound strained, soft and closed in, losing their extension & magic. The pink cloud starts to fade and darken, and it's time for the change back to my sweet-spot - the 2A3. With good tubes (I really like RCA bi-plates and even JJs), the 2A3 amp setup gets
very close to the 45 with much of the technicolor trip, along with the balls (sure, 3w of balls...
) to better handle some Blues, Rock or big scale orchestral. This is the perfect daily-driver for me and I don't even think about 45s that much.
And now that I've said that, I think I need a hit from the 245s today.