I guess it depends on what you care to spend. The better way would be to upgrade to the Touch AND get a linear power supply.
Of all the SB units, the Touch IS the best sounding on digital output and on analog.
Changing the switching power supply to a linear usually results in a lower noise floor. This is evident in a wider and deeper soundstage, deeper and tighter bass and cleaner and less harsh highs.
The Touch will also let you play 24/96 files natively. While some may not feel they can hear a difference, it is very plain to me.
A linear power supply will help you enjoy your SB3 now. It can also be used with the Touch, if you decide to move in that direction. The Touch can expand your enjoyment of all your music, but you will not get the full amount of benefit from it, without using a linear PS, IMO.