1. Keep the quad and get a 24-1Z MC multi switch. This is the only way to retain the Quad LNB. If you have a 5-2 ES available, you could try and use it with the 3A. It should work but there have been reports that the 3A does not work with the 5-2 ES.
2. Replace Quad LNB with a SLNB. The better SLNB to get is the LMX 501 if you want some flexibilityvto be able to connect single view decoder or an OVHD decoder. If this is not important to you, get the LMX 502Z.
Option 1 above is a very flexible solution, able to accommodate older PVRs. And also means no need to reinstalled the LNB.
The price difference used to be very small between the switch and an SLNB.
Octo LNB; 2 by 2x4 MS; 2 by ES 5-2; Dedicated PSU for LNB, ES's, MS's; HD PVR 4P x 2; Explora 1; DSD 660; FSM