From Marten Coltrane to Avalon Isis, Hansen King??

Maxx1973, What amplifier are you using with the Marten? That seems to be an inefficient speaker (300w recommended, 89db, 2.7ohm min). Could that be contributing to the lack of bass?

I am not sure about the power ratings for Vitus. However, I would not think twice about putting 600-900+ watts at 4 ohms onto the Marten.

For the Isis in a large room, with few exceptions, I would be looking at 400+ watts into 4 ohms as a minimum.

Other tricks to increase bass would be in the cables. The power cords on the source have the largest effect, followed by speaker cables and interconnects, followed by power cords on the amplifiers. Elrod power cords have a striking effect on the bass.

You have great speakers. All great systems take some time to build and refine.

Although I would not figure Nordost to necessarily have good synergy with ceramic and diamond drivers, I do not think that would necessarily limit your bass.

I would focus on the amplification. I personally feel that people vastly underpower their speakers. I'm sure the Vitus has a great 100 watts, but those woofers need real power to have them move air. If you can biamp, try to add-in something with muscle. I'm sure the Coltrane's are a special speaker, but looking at the specs, they are going to need some real experimentation to reach their full potential.