That's actually the reason why I am a little disappointed in the amp. I thought the tiny amp with it's claimed 50W RMS (or 40W @ 1% THD) would actually somewhat match the performance of my bigger AMPS. I don't know where the problem is.
I just had a look, i got a TDA7492 board from sure, not the same as yours but with a 24V supply it got more then loud enough on a pair of full range drivers but thats it.
I never measured the output, you get a reasonable amount out of them but i would put them in the "desktop use" category.
If i understood you right you have a pair of Jobst Audio ULB 8-Pro connected, the amp is seriously underpowered for those speakers.
You need way more headroom, music is fairly dynamic, the amp will clip at anny decent volume level on the peaks.
The next bigger one, the 100W TDA7498 boards, gets closer to what you want but since the whole thing is on a log scale...
But i have two of the TDA7498 board used on a semi active 2-way system for about 20 people in a small room in several occasions.
But i upgradet that to IRS2092 amplifiers with a beefy dual supply smps.