Re: attaching external speakers to an LCD television
OK.. there IS a menu toggle for 'Internal' and External. From your A/V component comment, I assume that there is no access to the TV-set's audio amp (except headphones and some *RCA jacks on the back for 'Audio Out') -- Right?
* RCA: the standard since forever, re all audio gear not using 'balanced' inputs and special Pro quality connectors.
That means yes, you do need (not a whole A/V Receiver with tuner and mondo input switching, but-) any old 'component' stereo amplifier (usually having bass/treble, volume controls and a low-level preamp (maybe not included in many post-LP-records models.)
Probably on the bargain shelf at Goodwill et al will be several such, or even with tuners you apparently don't want - Cheap. Odds today are against finding any of the great-sounding 'separate power amps' of yore -- they've all been sold for $$ on eBay, maybe several times.
A standard stereo cable-pair gets from your A/V output RCA jacks (ignore the Video one in a 3-set) to an amplifier input, a 'high-level' one like AUX, meaning: ~ 1V max input signals, and not millivolts.
Thence to any old zip-cord (or cut up an extension cord.) Do keep the +/- red/black 'phasing' correct: by following the ribbed wire in the zip-cord pair from AMP [+] output to SPEAKER [+] / Red connector. Out-of-phase gets you less bass.
In my Sony , I have two sub-options, besides Internal/External;
1) Fixed level out == means using the external amplifier's VOL-control.
2) Vol-controlled out == TV set Volume control varies signal to the external amp.
I use 2) into a NAD stereo amp --> decent speakers. Vastly better sound than built-in.
Maybe this failure was a Good thing, once you hear why decent speakers in adequate enclosures blow away something tiny, stuffed into a corner of the TV case. :-)
Luck,
I.