Amplifier for Infinity RS 5B?

Hello everyone!! I am from Romania and just entered like 2 or 3 years ago in this mad world of hi-fi. Also a new member on this forum. I have a beautifull pair of Infinity RS 5B which for the moment i drive with a Lafayette LR 1100 receiver (which by the way is in mint, mint condition :)1976 generation). The Lafayette is rated at only 25 watts per channel and I know that the Infinitys like a bit of power. I also have in test, from a friend a SONY TA F 690 ES amplifier. With the Sony the speakers sound much better. Any Infinity owners who can suggest a better amplifier for my speakers?
I am the owner of a pair of Infinity RS IIIB speakers. Vintage Infinity (such as POA3000 or POA1500 & Onkyo Integra such as the 508 works well. McIntosh 275 sound equally as well.
First of all thanks for the answer. I'll try to test other more powerfull amps. Hope I'll find the best, or at least a better combination.