Never enough USB Ports...

I'm using a Logitech wireless KB/Mouse (excellent BTW) for well over a year now and it uses one USB port, plus I have eyeTV which needs a USB, external Yamaha speakers connected via USB, an Epson USB scanner, a HP USB printer, a couple of card readers that need USB connections. I also want to get

I have two (2) USB expansion hubs; a Belkin 7-port hub, and a 4-port Belkin hub. Generally speaking, the eyeTV needs to be connected directly to the iMac as does my Direct TV STB via a USB to Null Modem to USB (uses Channel Changer Utility for on-screen remote), that leaves one (1) USB on the iMac to support all the other devices via daisy-chaining the hubs if I want to keep everything connected. I guess the alternative is to maybe not keep everything connected and plug in devices when I need them?

I've heard that while powered USB's can be daisy-chained, there is a certain amount of loss with each additional device connected, and that could be why I'm seeming to "lose" certain USB functions like eyeTV with too many other devices connected. Just looking for a solution that works.

There are two kinds of USB hubs, powered and unpowered. "Unpowered" is sort of a misnomer in that the hub still tries to utilize the USB power coming out of the computer. But as you add more connections, that power gets used up. The "powered" hub has its own external power source, and will support many more connections. I hope this helps.

Both my Belkins are powered by wall-packs... I never trusted the ones that weren't. But my understanding is that even with a power source, when you have something like eyeTV pulling on it, it might be sucking off more power than you think.

Funny you say that about your eyeTV. Cpl months back before i moved to a more inhabitable area i had my eyeTV though a USB extension cable to the USB 4hub, and never had a problem with it.
Mind you though i had my USB mouse in the same hub and then if i plugged in a Flash drive it worked well.
The only issue i have ever had is if i went to plug in my Card Reader it would shut down the eyeTV.
After it happened once or twice i then just plugged said CR into the second USB slot on my Mac.
You by mistakes and the sad thind was plugging in eyeTV into Mac wasnt a option because of distance and what not..

A powered USB hub of decent quality will work with most devices, except those that absolutely require a certain amount of bandwidth that is at or near the capacity of the bus. And I think that's exactly what you guys are seeing with the eyeTV.

When you connect a USB hub, regardless of whether it's powered or unpowered, you're dividing the bandwidth of that single port by the number of devices attached to the hub. So, if you've got a 4-port hub and all four ports are attached to something, each device needs to share bandwidth amongst that single port that has the potential for 480Mb/s.

Also, depending on the computer, not all USB ports on your machine are "dedicated" ports, so there may be some division within the computer's ports already. I don't know that this is the case with your iMac, but I have definitely have seen it with PCs that have a ton of ports.