Even if you had access to all these in a store, it is very difficult to discern differences much less preferences unless you have it in your own system for an extended period.
I'd suggest finding a source that offers you a 30 day evaluation period, pick one, and give it a listen. For example, AudioAdvisor.com carries the Cambridge Audio stuff (NAD also I think), has free shipping and will give you 30 days to decide. Your only cost should you return it, is the cost of shipping.
Should you want to try something else, I've found many vendors will offer an evaluation period if you ask.
I'd suggest finding a source that offers you a 30 day evaluation period, pick one, and give it a listen. For example, AudioAdvisor.com carries the Cambridge Audio stuff (NAD also I think), has free shipping and will give you 30 days to decide. Your only cost should you return it, is the cost of shipping.
Should you want to try something else, I've found many vendors will offer an evaluation period if you ask.