My Toshiba Satellite C55-A-14W Laptop but the sound quality is very poor and tinny.I like my music to sound rich and full,but the speaker quality on the C55 seems inferior ?.

sadly you have poor quality loudspeaker. the only thing u can do is plug in a powered speaker set into the headphone socket.

Laptops are notorious for poor sound performance, the issue is the speakers used on any laptop are not big enough to convey the deep rich bass some users require.

A workaround to this is to buy a good set of headphones when utilizing the sound system on a laptop.

Otherwise you need a better quality laptop; Some are made with premium sound speakers but again they too are limited due to the speaker sizes used in laptops. Not to mention the cost of getting one of these types of laptops.

I have the Toshiba Satellite C55-A5300.

I'm not sure about before the update, but after the windows 8.1 update my audio was pretty bad and had no bass at all.

In Control Panel ---> Hardware and Sound I found "Realtek HD Audio Manager" which has a tab named "DTS"

Once I hit the Launch buton I was able to apply settings for headphones and external speakers including bass boost.

My audio is now much better.

Hope this helps.

Normally the sound on the Vostro is lower than the Inspiron series as this is an executive office laptop.
All what can be done is you can download WINAMP and use to increase the equaliser /volume still further.
Also an active power speaker can be connected to the earphone socket to improve the volume to your desired level.

Is this the same for all audio, music, system sounds, etc.? Possibly a sound card or driver problem. Did it start doing this all of a sudden?

yes the microphone is poor quality in this model

try this mate:
http://logitech-en-amr.custhelp.com/cgi-bin/logitech_en_amr.cfg/php/enduser/std_alp.php?&cl=us,en&p_search_text=AudioHub&WT.ac=sc|troubleshooting||dd

one of my Speakers don't work