If your bass is lacking it's likely a component issue, not a "power" issue. In my experience McIntosh is not known for their bass performance. I'm not saying it's bad, but it doesn't have the reputation of say Krell for example.
So, you can solve this a few ways.
1. Add a quality subwoofer that can integrate with your speakers. I've used JL Fathoms in the past and they were excellent. There are lots of great subs out there but they do require effort to integrate them properly. The automatic configuration SW the JL had was really good. This is not a pitch for JL as many other offer the same type of auto setup.
2. Look at other components that have better bass performance. I've found that the preamp is typically the one component that will make the biggest change. Maybe you could audition one from a local dealer just to see if it helps.
3. The following is my preferred solution which is to use a source (DAC) that has some DSP. Purists will hate this idea but that's ok. The DSP allows you to tailor the sound to your liking. Adding a few dB of gain in the low bass region can really make a difference. Again, I'd recommend auditioning something and playing with it for a weekend to see if it solves your issue.
Good luck with your journey! I'm curious to see how your experiment works out.