mo' better bass: any substitute for watts?

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.

Ok, fourth time trying to post to this thread. I'm surprised that you haven't been asked yet what speakers you are talking about? Also, this could just be a placement issue. Have you moved your seating position and speaker position around enough to rule this out? If you do not already own the oppo 980 I would suggest getting the new 983,it has better sound quality from the analog audio output.

Something quite basic , that has not been touched upon here , is the configuration of those added watts .
Watts are a result of the amount of volts and amps going through a device . Amps are the driving force of the volts which do the work . It is the amps that will drive the volts through a tough crossover network and into a power hungry woofer .

You can have the same amount of watts with 2 amps (with higher voltage) or 20 amps (with lower voltage). But the 20 amp watts have the ability to do much more with a tough load . This is why some amplifiers will double down as the ohms decrease within a speaker , such as 100 watts into 8 ohms , 200 watts into 4 ohms , 400 watts into 2 ohms and so forth . Where as a low amperage amplifier may do 100 watts into 8 ohms and 125 watts into 4 ohms etc.

And yes , it usually costs more to make high amperage watts than high voltage watts .

Just a though .