KEN KREISEL DX500 Subwoofer…Quadrupled Setup…Enuf?!

When an audiophile asked me about adding Subwoofer to his audio setup,…is it necessary,…how many Subwoofer,…where to place it/them,…?

Necessary?…for me, I want that option

How many?… 2 units for stereo application

Where to place them?…preferably, near the main loudspeakers.

Our Teluk Intan audiophile just bought 4 units of KEN KREISEL DX500 Subwoofers for stereo application next to his WILSON AUDIO ALEXANDRIA loudspeakers!