Como vuelvo loco a María Santísima (ya me lo dice mi mujer) , escribí a Bose España y Bose USA. Esta es la respuesta de los USA.
Se podrá decir de Bose cualquier cosa, pero en atención al cliente, son magníficos. Han tardado 24 h. en respoinderme de ambos sitios.
Esta es la respuesta:

Dear Mr. Diaz De Alda,

Thank you very much for your message and the interest you show in Bose Corporation and our products.
We are pleased to learn you do enjoy your Bose Acoustimass 6 Home Entertainment System.

Regarding the parameters, they should indeed be adjusted to LARGE and not to SMALL.
Indeed the small loudspeakers cannot reproduce the low frequencies. This is being done by the bass module.
Nevertheless the settings should be on LARGE as these frequencies are being sent to the bass module first.
The crossovers in the bass module need to have the LARGE signal, which they split up in the signal that is being sent to the cube loudspeakers and the signal that the bass module reproduces itself.

We trust to have you herewith informed sufficiently.
In case of any further questions, please do not hesitate to contact us.

Sincerely yours,

Martin van Manen

European Export Department

Bose B.V.
Nijverheidstraat 8
1135 GE Edam
The Netherlands
T: +31 (0)299 - 390 750
F: +31 (0)299 - 390 190
E: export_europe@bose.com
W: www.bose.eu

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From:
Sent: Tuesday, September 05, 2006 5:44:07 AM
To: Support_INTL
Subject: Technical and Service Requests
Auto forwarded by a Rule

Goood morning.
I am the owner of your Bose AcousticMass 6 Series III, from two months ago. I am really satisfied with it. Of course, and as you recommend in the owners guide, A/V setting parameters are adjusted as LARGE, and crossover frequency is adjusted to 80 Hz.
Well, reading some opinions in some forum, expert people recommend to adjust parameters to SMALL and crossover frequency to 100 Hz. They say that front speakers are not able to reproduce low frequencies, and for that is better to send those frequencies to the subwoofer.
What is your opinion? What is better and why?
Thank you for your quick answer