Generally speaking, a more powerful amp may give better bass but it also depends on the character of the amp itself. I am pretty sure you will get better and more defined bass if you substitute your 35W NAD amp with say a Krell integrated. Also, Jaybo is correct in that you won't need to crank up the volume higher to appreciate more bass with a substantially more powerful amp. Even that, your speakers may be limited in bass response, and the suggestion of adding a subwoofer is good idea if the frequency range of your Rega speakers does not extend down to 35Hz or so. Adding a more powerful amp won't help much if your speakers ain't up to it.