Yamaha straight enhanced sound

I think so, yes. Both my Yamaha receivers in the kitchen and bedroom do the same. If you select "Information" from the menu as you switch between "Straight" and "Movie", you will see the effect of switching. It must be that once the sound is not set to "Straight", once you do any sound processing, that the sound is no longer Dolby True HD or DTS-HD Master Audio. I don't find that fact distressing, and on balance having experimented with the various available surround modes, I prefer both my Yamahas to be set to "Movie Spectacular" rather than "Straight".

The Straight Enchancer and 5 Channel Enhancer modes are designed to improve the sound of compressed audio, like MP3s. As DTS HD and Dolby True HD are essentially lossless, or at least hi-res the enhancer mode really should not be required. If you're listening in the enchancer mode then the original sountrack is being changed through the processing, rather like using one of the Cinema DSP modes.

I listen to mine straight.

What I have begun playing with is the equaliser when listening to music.

going from Flat to Through, is it better to just set to Through and dismiss

the equaliser all together what does it actually do.

I believe that straight or pure direct or standard are best for all 'decent' sources inc DD DTS etc and for CD sources. I only use processed modes for PL etc. I recon if all parameters of the set up are optimal then further processing is corrupting the source. Having said that, try each and use whichever sounds best with your source, your setup, your room and your ears. Sorry you can't have my ears but then they are getting a bit worn now.

Cheers

Just to  clarify my misunderstanding. When listening to Blu-Rays, I use Movie Spectacular mode. For everything else, I use Straight. But I do not use the Enhancer mode at all, never.

Sorry SonofSJ but I am surprised you wish to use a processong mode using the 'best' source ie bluray. With 5.1 discrete channels I would think you should avoid processing. I would ask if your kit is optimally connected or setup. I am sure a greater expert than myself will confirm or refute this.

I know nuffin' 

Yes as far I as I know you only will get Hd in 5.1 by setting amp to straight so surely it will be better.

Music sounds better to me when its set to through so there it is.

thanks

Straight is best unless your speakers are a bit too bright or dull, then you'll need to tweak the equalizer and then straight isn't the best sounding.  More likely to happen with a small sat + sub setup as they rarely have a flat response.  Trust your ears, not the perceived wisdom of the crowd.