Soooo, the test results.....
Let's start from the beginning. We tested both amps with Infinity Kappa 9.2 loudspekers.
First, we listened to some tracks on the B-3s, then we connected the Accuphase, but since it was couple of minutes later, we didn't remember perfectly how the B-3s sounded, and it seemed pretty much the same, except for the bass, where the B-3s had more kick. It's that sort of bass you feel inside and that's what the A-47 lacks.
Then we had decided we want to do an A/B listening test. Since I've got only one pair of loudspeakers, we put the source into a mono mode, connected one B-3 in a BTL mode to the left channel, the A-47 in a bridge mode to the right channel and corrected the volume for both channels, so the both channels were ballanced. Then we played some tracks. We were turning off and on channels in random to listen just to one amp at a time.
Well, to my ears hights were pretty much the same, however, mids on the B-3 were clearly superior, the A-47 sounded a bit "veiled" to me and again bass was superior on the B-3. It's got more punch.
But my room is not perfect and the speakers are not perfectly centered, one is closer to a sidewall and the other one is a bit farther. So, we reversed the channels and did the test again. This time, the highs and mids sounded pretty much the same to me, but the bass was still much better on the B-3.
So, the conclusion is, if I average the last two tests, the B-3 has the same hights, a tad better mids and a lot better bass. I am quite happy with these results, I don't need to buy new amp to upgrage the sound. But what is quite funny or maybe sad, is that new amp, that is supposed to be the top of the line, can't compare to a 45 year old crap.