Help eval my 1990s era audio gear - yamaha + epos es12 speakers, misconfigured?

[barrelrider]

I know almost nothing about audio gear. What I have should sound better than it does, I'm trying to figure out why.

era 1990:
Yamaha RX-730RS receiver
Yamaha KX-W602 cassette deck
Yamaha CDC-705 cd player
era 1999
Epos ES12 bookshelf speakers

When I turn the volume up, it sounds ok but the bass seems to be MIA. When I bought the speakers they sounded great in the store but never really measured up at home. There are four jacks on the back of each speaker (treble/bass) but the cables end up going into only two jacks on the receiver; that must be normal? The speaker wiress are good quality (tend to get oily over time) and are not very long, and were provisioned for me by the store that sold the speakers.

What I"m focusing on now is the sound. Is it possible that the speakers are not hooked up correctly, with the four wire for each speaker going into just two clips on the back of the RX-730RS?

I'm trying to figure out if this gear is just too old to fiddle with and if I should start over. I know new equipment has a lot of more digital era features, I'm not sure I need any of that. I listen to all kinds of music.

 

[americanaudiophile]

The speakers have bi-wire speaker terminals. Quite common on audiophile speakers. There are two ways to connect them. You connected them the first way which is fine.
1. A single two conductor speaker cable connects both the tweeter and woofer terminals to the same pair of terminals in the receiver. There should be a connection between the two positive terminals and the two negative terminals. If you don't have this connection you will here only the woofer or tweeter but not both. It's usually a metal plate that does this.
2. Remove the jumpers between the + and - terminals and run two pair of 2 conductor speaker cables in parallel back to the same two speaker terminals in the receiver. On some speakers you get less intermodulation between the tweeter and woofer because the extra length speaker wire tends to reduce the interaction of the speakers which results in a clearer midrange.
I think your problem is that while the Epos are good speakers they are designed for smaller rooms that are more typical in the UK. They are not really happy in modest to larger rooms. The quality of the bass that is there is good but not what people have grown used to with HT systems that have subs. If you are happy with the overall sound but want deeper louder bass than adding a powered subwoofer will do the trick. If you get one like the Paradigm or Martin Logan subs that have powerful room correction you can fix placement and room problems. Even though the receiver doesn't have a sub out it does have a preamp out - amp in loop. You would use one female to two male RCA Y splitters instead of the loops that now connect the RCA jacks to create a line level out for the sub. You want a sub with left and right line level inputs.
There are a lot of improvements that you can make but it depends on how much you can spend. You can get better sound out of the Epos than you are getting now. Do them one at a time so you can hear what each contributes.