addition of 2nd pair of speakers

I own a Linn Magik component system. I'd like to add a 2nd pr of speakers which my amp can't accomodate. Can anyone recommend a good, quality speaker selector box I can purchase to accomplish this, as I am concerned about having it provide the proper power protection especially when playing both prs. simultaneously.
I had a Niles box that I had 4 sets of speakers hooked up to. It degraded the sound. I'm not trying to knock you, but maybe get bigger speakers, or a second system. I use Linn for all of my sources and really like their equipment, but there has to be a better way than a selector box. Happy listening.
Bryston speaker selector boxes. Can get them in two or three or four pair speakers. The two and three pair type also has the feature of a headphone output. Little to no loss in my use. Only gripe would be the speaker ternminals are very close together, best to use banana plugs.
The Bryston selector did not degrade my sound at all. Completely agree about the speaker terminal observation above. Use bananas if possible.
Doesn't the answer lie in the capability of the amplifier as it relates to the specs of all the speakers being driven?

I know Linn products are well received and for good reason, nevertheless, I would recommend reading the manuals for your amp and speakers to determine if the amp has the capability of driving both speaker pairs simultaneously.

Glenfihi and Jax2, did you use the Bryston selector box to run multiple sets of speakers simultaneously or to switch between sets running only one set at a time?
In my case I used the Bryston 2 way selector box to at times run one pair of speakers, at others to run both at same time. As many amps/pre have no headphone output, I used it for headphone use as well. For more info if not found on the Bryston web site, one might check the audio advisor site. The Bryston works well, and seems built to last, with excellent sound quality. As with all such type, they present your amp with the proper load to protect the amp, and drive the speakers properly. Some units have a hi/low power switch, as is the case of the Russound speaker selector box with headphone output I also have. This older unit would seem dated as it uses a barrier strip for the speaker connections. I also believe Parasound makes a speaker selector box.
Bryston unit does not provide protection for speaker or amp. It is only a switching device. I mis-spoke in my earlier post on the protection segment. Thanks to rantes7 for bringing it to my attention, he having checked with audioadvisor. My checking the unit and the schemactics confirm such. The unit made to provide the best sound quality possible. The protection left to proper matching of sets of speakers, ie using both 8 ohm speaker pairs. Along with amp that could handle 4 ohm load when necessary. My experience with my gear has never encountered any problems. I've used the Bryston with different sets of gear.
The Parasound unit according to AA has impedence matching.
Sorry for any confusion and thanks once again to rantes7 for bringing it to my attention.
I bought an Acoustic Research AR1108 at a pawn shop to switch between two sets of tower speakers. It worked perfectly. It has built in protection circuitry. I ran it off my B&K 200w amp. I did not hear any audio degradation at all.

Thanks for the reply, this has been helpful for me.
Adcom also makes a speaker selector switch. Does anyone know how it compares to the Bryston?