Well let's make it unanimous. Definitely Speakers first.
Your Receiver model number is a RX-V379. The manual sort of gives power output for both 6 and 8 ohm (nominal) speakers. I was quite shocked at some of the "specs" given for the amplifier section from a Yamaha Manual. So use the conservative ones.
For 2 channels driven into 6 ohm load; 20 => 20,000 Hz; 70 W + 70 W for L&R Front Speakers (0.09% THD). They don't give any rating for all 5 channels driven, which is a shame. You should expect less power per speaker, the more channels driven, at the same distortion level. (0.09% THD).
I recommend you buy the 3 fronts speakers with you first installment if you are looking above the Pioneer Andrew Jones series SP-PK52FS 5.1 package). It's important that all three are the same speaker, or at least supplied by the manufacturer for use as Left -Center-Right (LCR) package. If you find something you like that's efficient (say like the CCB-8, at 94 dB / 1m / 2.83V in Half Space) your receiver will be able to drive them. Then I'd re-use you present speakers for the Surrounds and Sub until you replace them later. The Sub would be next, with surrounds last.
I have a pair of SP-BS22-LR Bookshelf Speakers for my computer setup, and they are amazing for the price. The SP-BS22-LR carries a 6-ohm load and has a sensitivity rating of 85 decibels. If one were to assume a 50 watt output from the RX-V379 for all 3 (using a SP-BS22-LR as the center) then output measured at about 10 feet would be 97 dB. Loud but only about half as loud as the CCB-8s mentioned above, who would output almost double the sound at over 106 dB. (A sound pressure increase of approximately 10 dB is considered as a doubling of the volume.)
The Floor Standing SP-FS52 Loudspeakers and SP-C22 Center-Channel Speaker have a bit better efficiency and should be about 99 dB. So if you bought the Pioneer Andrew Jones series SP-PK52FS 5.1 package without the Sub, it could be loud enough for you. I would certainly recommend a better sub (as would most folks here) instead of what comes in that package.
I just noticed you can buy the 5 Pioneer Andrew Jones series speakers on Amazon for
$375 US Funds which is amazing. I know these were discontinued, but obviously there is still some stock around. I don't know of a better sounding package at that price. If you head down that road, you should consider putting the Floor Standing SP-FS52 Loudspeakers on small (~10 to 12 inch) stands to bring them up to ear level (when you are seated.)
Then you can start saving for the Sub with a $425 head start.
I hope this is helpful.
