I WANT TO CONNECT HEADPHONES TO 1/4 INCH PHONE JACK ON TECHNICS AMPLIFIER IN A WAY THAT WILL CUT OFF SPEAKERS SO THAT AUDIO IS SOLELY THROUGH THE HEADPHONE. HOW DO I WIRE THIS USING THE PHONE JACK ON THE FACE OF THE AMPLIFIER, MODEL # SUG91? WHEN I PLUG IN THE SONY WIRELESS HEADPHONES--MDR-RF925RK--I STILL GET AUDIO THROUGH THE SPEAKER SYSTEM.

Did inserting the headphone Jack cut the speakers off before it stopped working? If it did then you should look at the headphone jack socket inside the unit. The terminals could be either bent out of shape, broken or just dirty.

IF the head phone jack works and the speakers don't then the issue is the jack. The jack disconnects the speakers when the headphones are plugged in. I have seen the jacks get the connections bent out of place by having pens and other objects stuck in the head phone jack. Ignore the subwoofer it is on its own circuit,

Normally , you would expect the TV sound to stop when headphones are plugged in. Obviously not in this case. If you have a set of headphones, try them and see if the TV still has speakers on. If it does, then there may be a setting on the setup of the TV to get headphones to work. If the TV speakers stop, then I would think that the Logitech are not compatible with the TV. The only other thing would be is to get into the TV and disconnect the TV,s own speakers. If the wires are soldered on and not terminal connected, carefully cut 1 of the wires off near the speaker. If 1 wire is cut, the speaker wont work. Make sure both the TV and the additional speakers (If they have their own power supply) you are using are unplugged from the power before you go doing this...!

The speaker cutout feature whenever the headphone jack is connected is a hard-wired feature of the headphone connector, and cannot normally be bypassed without further electronic circuitry and the associated surgery to install a custom modification in the TV. In order to keep the TV speakers on while using the sound elsewhere, you will have to take the audio output from the IR Audio port, if there is one.

The "phones" connector on the front is for headphones. You need to connect to the "aux' or "line" input which is usually on the rear of the receiver. It is usually 2 RCA jacks so you'll need to get a patch cord with a 1/8" mini phone plug on one end a (2) RCA plugs on the other end.

Connecting Full-Size Speakers
1. Step 1 Insert the red and white plugs on a set of RCA audio cables into the right and left audio "OUT" jacks on the back of the TV.
   
2. Step 2 Connect the other ends of the cables to a free pair of audio "IN" jacks on the amplifier.
   
3. Step 3 Strip 1/2 inch of insulation from the speaker wires, and connect a pair of wires to the left and right terminals on the back of each speaker using the red wire for the right audio connection and the other wire for the left.
   
4. Step 4 Connect the other ends of the speaker wires to a pair of stereo speaker terminals on the back of the amplifier. The wires attach by raising spring-loaded clips on the back of the amp to reveal a hole for inserting each wire.
   
5. Step 5 Set the amplifier selector to the set of audio jacks connected to the TV to enjoy stereo sound from the television.
   
Connecting Self-Powered Speakers
6. Step 1 Insert the RCA plugs on the Y adapter into the TV's Audio "OUT" jacks.
   
7. Step 2 Connect the mini-plug on the wire attached to the right-hand self-powered speaker to the mini-plug jack on the Y adapter.
   
8. Step 3 Plug in the audio cable and mini-plug from the left-hand speaker into the Audio "OUT" jack on the back of the right-hand speaker.
   
9. Step 4 Connect the AC adapter to the power jack on the back of the right-hand speaker, then plug the adapter into an electrical outlet.
   
10. Step 5 Switch on the external speakers and adjust the volume.
    

This could be either a fault on the headphone socket itself, or on a speaker switch. It depends on how the insertion of the jack plug into the socket affected the sound before the fault. If for example the sound was cut off from the speakers, then it's likely the fault is the socket itself.
On the other hand if you have to press a button to switch the speakers off the fault will be connected with the that button.

It is important that your headphones are STEREO tyoe as a monaural 1/4 inch plug will short out one side of the output audio.

Make sure the plug is fully seated as it has a switch in the unit that disconnects the speakers typically when headphones are plugged in.

If your speakers do not get cut off when you plug in the headphones, it is POSSIBLLE that the switches on the jack have been broken. This would require servicing.

The lit indication ("amp bars") proves that the aduio signal is getting through the unit's circuitry @ least to that point; lack of sound @ the spkr & headphones indicates the amplifier portion of the circuitry is either inoperative or disconnected from the load (i.e., either the speakers, or the headphones). A common cause of this type of problem cropping up unexpectedly is the headphone jack itself; in most products of this type, the audio path from the amplifier output to the speaker connection runs through the headphone jack, so the the speakers may be "turned off" when the headphones' plug is inserted into the jack. If the unit's owner uses headphones regularly, the most common problem to be found with the jack is loose solder connections to the printed circuit board's traces from the jacks' lead(s); in units with this problem whose owner's irregularly use the headphones, it's more common to find oxidization of the electrical contacts within the jack itself.

I would say it is because the unit does not have a built in amplifier. The speakers are powered PC speakers of studio monitors I am guessing. Try plugging the headphones into the headphone jack of the speakers if they have a headphone jack or try a set of powered headphones out of the Edirol and see if it helps.

That should remedy the problem.