Sorry guys and gals - I've been tied up for the last few weeks and haven't had a chance to "catch up" on the latest posts here. So heres the answers to some of the questions posted above.
Ion Xpak and Nexus SP1 (preamp).
All the Xpak power supplys have the same voltage output at 22V x2 and have the same connections.
The original Xpak1 was used with the original black "industrial" looking Ion Obeleisk 3X
The later version of the Xpak1 used with the later 3x (with the neater front pane; and the red Ion label) was the same voltage but a much higher VA rating to improve supply regulation and sound quality.
either version will work with either 3x but there will be some inprovements in sound quality and performance by using the later Xpak1.
The Nexus range used the Xpak2 which was essentially the same as the XPak1 but it had 2 outputs to drive the SP1 preamp and the original Nexus power amp.
Again the XPak1 can be used to power an SP1 preamp but it only has one output so it cant power the power amp as well..
MC or MM ???
This applies to all the Nytech amps (CTA/CA) and the preamps (CP112/122).
The markings on the back should tell you wat is in the amp but if the input card was changed by a dealer the input label wasn't changed which causes confusion.
The easiest way to tell if its MM or MC is to try it with a record deck with an MM cartridge.
If the resulting sound is OK with the volume just under half way for a "reasonable" sound level then the card fitted is almost certainly MM (S 1.5mV)
If the resulting sound is very muffled with very little treble then its likely to be moving coil and likely to be an MC1 as the MC2 was only used for a couple of very low output cartridges.
Its also possible to tell by measuring the input resistance (with the amp OFF!!)
Using a multimeter on the ohms range measure between the centre of the disc phono socket and the outer earth (black to centre, red to earth)
If you get a reading of greater than 10k ohms then the input is MM
If you get a reading of around 470 ohms then the input is MC
Finally using a CXA252 crossover amplifier as an amp
You are correct! the statement
"it has normal banana plugs at the back and if you want to use as a active system just connect the din plug to the high frequency and the banana to the id base connectors. normal connection to the banana speaker connectors enables bypassing the cross over part."
is pure nonsense!
The DIN speaker sockets are connected in parallel with the 4mm sockets so they are exactly the same outputs so you cannot bypass the electronic crossover by doing this.
It is possible to use a CXA as an amplifier but only by removing the crossover board and linking the inputs directly to the PA modules. However as its the same power amp modules as used in the CTA/CA I wonder what the point would be. The CXA is more valuable to someone who is looking for one to make an active system then it is as a power amp. If you want to really improve your system then look for a CPA602 power amp but they are even harder to find on the SH market!
Hopefully this info is helpful!