Rega Maia / Cursa combo vs. NAD C260 / C160 combo

The Nad be it the 260/160 combo or the very similar 370 integrated amp will give you a tremendous amount of power and an open transparent sound with superb bass control. This new NAD equipment is quite a surprise and unlike their older equipment.
The Rega Gear will have considerably less power with a warmer smoother more tube-like presentation. The Rega I believe has a phono preamp built in.
It all comes down to what speakers you are trying to drive, I would say this is definatley a try before you buy situation as the sonic signatures will be quite different and it can sometimes be frustrating to move down in power.
There are a lot of great deals in Integrateds at this price range which may bring you better performance for the dollar.

For solid state the Creek 5350se is incredible at $1500 in th world of tubes the Rogue audio tempest is wonderful at $2195.
I would definately upgrade your speakers before considering an amplifier upgrade the NAD combo you have is actually very good and you would have to spend quite a bit on speakers before you begin to realize it's potential.
Nice speakers in the $1500 range are the Meadowlark Kestrals, overall one of my favorite speakers, the new Audio Physic Yara, used Audio Physic Spark III's if you can find a pair. I would upgrade the speakers long before I thought about upgrading your amplification.