Off-topic but why did your friend get three low-end computer speakers? Does he use it for multiple computers? Because he could have a VERY nice RP5/RP6/BX5a/AE5 + sub 2.1 setup for that priceMathemabeat, I personally own the Z-2300 & Creative T3. Out of them day in day out I choose Z-2300 for music, movies & games. My second choice is Z-623. I also have an Audio Engine 5. But I am not going to compare AE5 with Z-2300 since it is a 2.1 comparison.
My best friend has Promedia, Z-2300 & Z-623. He also have Klipsch HiFi products adorning his house. He is a crazy Klipsch fan-boy. He bought the Z-2300 after hearing mine. Though according to him Klipsch is a HiFi company and should not be compared with Logitech, but according to him this Z-2300 is more than a match to the Promedia's. That is the reason why he bought the Z-2300 at first. I have listened to the Promedias for hours & days. And both me and my friend choose Z-2300 & Z-623 over Promedia.
I have heard the Corsair SP2500. But only for half an hour in a showroom from where my friend bought the Z-623. But that was an intense half hour session. I took my own songs(FLAC) in my pen-drive to find the strengths & weakness of SP2500.
SP2500 have Z-2300 type of chest thumping bass. Z-623 also fall in the same group. SP-2500 like the Z-2300 have the ability to decimate the Promedia with its bass. The SP2500 satellite behavior is uncertain. Tones seemed to be accentuated than Z-623 in some areas while in some other areas tones are missing.
For example: in a duet song I can hear the male voice very loud while the female voice was weak. Playing the same song on Z-623 the male voice is not as loud as SP2500 but then the female voice is not that weak either. Ditto Promedia.
I seems that Z-623 & Promedia satellites are more stable & have an uniform loudness through out the frequency range. Both of them are very smooth & subtle. On the other hand SP2500 satellite acts like a bare chested beast & are are ultra loud. First time out you are gonna love those SP2500 not doubt, but on the long run I do not know.
The difference between Z-623 & Promedia satellite came into light when i played the Yanni's "Nightangle" track. That track has so many audio instruments & the 10-20kHz advantage of Z-623 was clearly present but the difference was not sea apart . Still Z-623 was better.
Note: My friend believes that Klipsch have downgraded their Promedia recently. According to him his first Promedia bought way back in 2000 was way better than his recent 2010 version. Unfortunately that set went bust in two years time so I cannot verify that. Since this is a current topic under discussion we should stick to the recent version.