I have a reciever and speakers, that works fine, but is a little light on the bass for my taste, I also have a decent set of old, powered computer speakers with a subwoofer, they have a 1/4" jack connection while my reciever has standard speaker wire inputs (red and black for left and right) I currently have the computer speakers plugged into the headphone jack on the reciever, which works alright but I have this feeling that it may not be good for either the reciever or the computer speakers. Also aesthetically it just looks crappy having this wire coming out of the front of the reciever. Is it 1: possible to convert a 1/4" jack to plug into the regular speaker outs on the reciever and 2: is that going to ruin the reciever or powered speakers? If #1 is possible, how do i do it, I am generally capable with this kind of thing but have no special equipment or skills.
High level signals are usually referring to speaker level outputs. Meaning the signal is ready to be fed to a speaker without further amplification nor does it need a separate power amplifier.
If you have powered computer speakers, you can use the line output of your receiver to connect them. you would need a stereo mini plug to RCA adapter. You do not use the speaker outputs of the receiver to connect the powered computer speakers.