DDC:
12 Volts. No need for relay, no 230 V in w/c internals.
Probably very reliable. (Used in Apple system.)
Small.
Pumps very good in a restrictive loop.
Amazingly smooth almost no vibrations.
Rather quiet.
Eheim:
230 Volts. (Standard.) Extra PSU load thus spared probably neglectable.
Known reliability.
Very good flow if the line is split to reduce restriction. Poor head.
Vibrates like a sex toy. (Or so I've heard
)Extremely quiet.
Yes, I can confirm the Laing DDC is noisier than the Eheim 1048. Even if undervolted to 8V, as I run it. (@ 7V it stops.) For a SPCR hardcore silencer, it is too noisy to use unless you isolate it. Isolation, however, is easily achieved thanks to the small size and almost non-existent vibration problem. It vibrates about as much as, or actually slightly less than, my WD740 Raptor HDD.
The Eheim on the other hand is impossible to use in a quiet setup without thorough vibration isolation. Some soft padding won't suffice. Mine hangs in silicon cords and has soft tubing connections.
As a bonus I note running the DDC on an Innovatek Fan-O-Matic channel presents no problems as it stays within 12 watts. Yummy.
