1 or 2 speakers ?

[cacole]

One well-baffled speaker will produce better sound than two poorly-baffled speakers, and you also encounter the problem of impedance matching when trying to use two speakers.  The most important criteria is using a speaker or pair of speakers of the proper imedance to match the decoder's amplifier.

[Texas Zepher]

I have several of the 16 x 35 mm speakers around.  Should I put in 1 or 2 of these?  Does two make much difference?  Or should I get something even a little larger?

One large speaker is better than two small ones for the hook up reasons davidmbedard stated.  I got a bunch of really big ones -  about 28x84 mm which work really well when space is not an issue.  They are also rated at 3W so there is no chance of frying them.
 

Like other Soundtraxx, the amp is 1 watt, I believe.  Adding two will diminish the total power available.  Is the sound gain still worth it?

If you are just after volume (eg. LOUD) then it is questionable.  If you are after better sound quality, then the more air you can move the better the bass reproduction, and two would definitely be better.  

Be careful when selecting speakers as many of the tiny ones are rated at 0.1 watt not 1 watt. 

[Anonymous]

I have a Tsunami install to do, with lots of room.  I have several of the 16 x 35 mm speakers around.  Should I put in 1 or 2 of these?  Does two make much difference?  Or should I get something even a little larger?

Like other Soundtraxx, the amp is 1 watt, I believe.  Adding two will diminish the total power available.  Is the sound gain still worth it?