No speaker "large" seting sub=Yes or No
you Onkyo TX-SR805 manual is located online a:
http://63.148.251.135/redirect_service.cfm?type=own_manuals&file=TX-SR805_875_B_En.pdf
To set you speaker levels you have Automatic Speaker setup ( Audyssey MultEQ XT) see page 55. This will give you a good starting point for sound levels.
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Your Onkyo TX-SR805
does not have a "SMALL" / "LARGE" speaker setting.
On your Onkyo TX-SR805 Connecting a Powered Subwoofer ( from page 59)
Using a suitable cable, connect the AV receiver’s SUBWOOFER
PRE OUT to the input on your powered subwoofer.
If your subwoofer is unpowered and you’re
using an external amplifier, connect the SUBWOOFER
PRE OUT to the amp’s input.
Speaker setting "large" or "small" does not indicate speaker size. If the speaker is set to large, the speaker will receive all frequencies. If the speaker size is set to samll then there is a cross over frequency ( usually between 50Hz and 200 Hz), any frequencies below the crossover will be sent to the subwoofer pre out. You do not have a speaker=large or small setting option. That is okay. On you receiver it appears that if you set the subwoofer=Yes or it is detect from running the auto setup, then it has the exact same effect as if you had specified your speaker size as "Small" .
And to confrm what I said (speculated) above from page 87 (step 5):
Use the Up and Down [ ]/[ ]
buttons to select “Front,” and
then use the Left and Right
[ ]/[ ] buttons to select a
crossover frequency.
Note:
• Fixed at Full Band if Subwoofer
(step 4) is set to No.
Advanced setup starts on page 86. There you can set subwoofer=Yes or No