I'm not sure we addressed your questions with enough information to put the puzzle together on your own.
First, the "A" and "B" thing. Don't confuse this with channels. With a stereo receiver, there are always (and only) two channels - right and left. When you hook up a pair of speakers, one speaker carries the left channel, and one speaker carries the right channel.
Each speaker requires a pair of speaker wires...one wire of the pair designated as positive, and one as negative. The pair of wires provides for a complete circuit between the receiver and the speaker. Looking at the back of your receiver, you will see that there are two sets of speaker terminals...A and B. Each "set" accommodates ONE pair of speakers (a right channel speaker, and a left channel speaker). As implied above, a single pair of speakers will require
two pairs of wires. It is important to assure that the positive connections on the receiver go to the positive connections on the speakers, and that the negative connections on the receiver go to the negative connections on the speakers. If they are mixed, the speakers will not have the same polarity, they will be out of phase and cancel out much of each other's sound output.
Hopefully that clarifies the difference between channels (left and right) and the A/B speaker terminals. When you set the speaker selector on the front of the receiver to A, the pair of speakers connected to the A terminals is active. Same for B.
Okay, now on to amplifier power and speaker power. For an amplifier (receiver, in your case), its OUTPUT to the speakers is measure in watts. Your Kenwood is rated to deliver UP TO 100 watts of continuous output PER CHANNEL (that is, to the left channel, and to the right channel). This rating almost assuredly assumes speakers with a nominal (average) impedance of 8ohms...as is the case with the Lancer 77's and the KG.5's.
The power rating of your
speakers refers to the amount of INPUT power (watts) they can handle. Speaker power ratings are not as reliable as amplifier power ratings, and should only be used as a rough guide. They are commonly quoted as the amount of continuous power that can be handled, but sometimes PEAK power figures are provided instead (or in addition to). Pushing speakers beyond their power handling capabilities will cause the speakers to distort in various ways, and will ultimately damage them badly. This can happen fairly quickly if the power is significantly above what they can handle.
Moving on....just because your amp is capable of producing more power than your speakers can handle doesn't mean that you need different speakers. All it means is that you need to take some care with the volume knob! It's usually not hard to tell when you are pushing your speaker too hard.
Also, you need to understand that you are VERY unlikely to ever be pushing 100 watts of continuous power to your speakers. Your actual continuous (average) output is a function of the sensitivity of the speakers you are using. The sensitivity specification describes the loudness that a speaker will achieve with 1 watt of input from the amplifier, measured at 1 meter.
For example, the JBL Lancers have a sensitivity rating of around 86dB (decibels). Subtract 8-10dB for listening distance, add 3dB to account for the second speaker, and you are around 80dB at a normal listening distance with 1 watt of power. Everyone's hearing is somewhat different, but 86dB would be considered a moderate to slighly loud volume level. Now here's an important thing to understand - each additional 3dB of loudness requires a DOUBLING of power. So, to get from 80dB (which takes one watt with this particular pair of speakers) to 86dB, you'll need 4 watts of continuous power. And by the way, 3dB is generally defined to represent "the lowest amount of change in loudness that is distinctly noticeable".
Sounds like you have plenty of power to spare, right? Heck, even if you want to move up to 95dB (which is starting to get quite loud), you'll only need 32 watts. Still plenty to spare! But wait...there's another variable that you need to understand; specifically the role of dynamic peaks in the equation.
In a good recording, brief/transient peaks in the music will be 9-12dB louder than the "average" loudness of the recording. If your amplifier is not capable of delivering the power required to accommodate these peaks, it will "clip" the signal, causing audible distortion. A bit of clipping is no big deal, and adds little distortion. But as clipping gets worse - and it will do so quite rapidly, given the logarithmic relationship between power and loudness - it will quickly degrade your sound quality in a very noticeable way. Often, people think their speakers just aren't very good, when the real problem is their amp (or, more specifically, the real problem is that their amp doesn't have enough power to cleanly achieve the desired loudness and the associated dynamic peaks).
Let's go back to the JBL's, pumping out 95dB with 32 watts of continuous power. In this scenario, peaks of 9dB will require 256 watts (32x2x2x2)! This is more than the amp can deliver, and more than the JBL's can handle. So let's back off on the volume....down to 89dB. Now we're only using 8 watts of continuous power. Peaks of 9dB will require 64 watts. All is good...the speakers can handle it (normally, a speaker's peak power rating is at least double it's continuous rating), and the amp can handle it. So, 89dB is approximately as loud as you're going to get with the JBL's before you start to degrade your sound quality and risk damage to your speakers (or, in the case of heavy clipping, damage to your amp).
The KG.5's are more sensitive than the JBL's...they will require less power to achieve a given loudness than do the JBL's. Specifically, the sensitivity rating for the Klipsch is 90dB, and they can handle 50 watts of continuous power and 200 watts of peak power.
If you run them together (that is, if you choose A+B on the speaker selector), there are three issues that you will need to be aware of:
- The difference in sensitivity means that the Klipsch are going to be louder than the JBL's...so what you hear is going to be shaped primarily by the Klipsch.
- The sonic character of the two different speakers may be complementary if you're lucky, but is more likely to be at least somewhat incompatible.
- If the A and B connections are wired in parallel, all speakers will get the same wattage from the receiver (just as they would if only one pair of speakers was active). However, impedance will drop to 4 ohms...which will double the demand on the power supply of the amp/receiver. Some amps - those with better power supplies - can handle this load. Others cannot. Sounds like your receiver has an accommodation for this situation....the switch you mentioned probably puts a resistor into the speaker circuit to increase the impedance and lessen the strain on the power supply. Unfortunately, this may also degrade your sound quality a bit, and it will reduce the effective sensitivity of your speakers. If you have the manual, refer to it to verify how/when to use the impedance management switch.
