Tape outputs cannot be used to drive speakers, because they can't supply significant power (and also because the volume at tape outputs is not controlled by the volume control). And depending on the design of the amp it is possible that it could be damaged if speakers are connected to those outputs.
There is no direct relation between the 4 ohm and 8 ohm impedances and the volume level. It depends on the sensitivity or efficiency of the particular speaker (i.e., the sound pressure level (spl) the speaker produces in response to a given input voltage or power level). For a given input voltage, a 4 ohm speaker will draw twice as much power as an 8 ohm speaker, but that does not mean twice the volume. Based on a quick check, it appears that your two speakers have roughly comparable efficiencies. I believe it's "JMLab Micron Carat," btw, not "JBL Micron Carat."
I don't think that there is a good way of connecting all three speakers to the Creek 4330 if you want to have them all playing at once. There are some references on the web to the 4330 being able to drive 1 ohm loads briefly, but
these instructions from Creek state "not recommended for use into more than two pairs of 8 ohm loudspeakers."
If you don't want to play the speakers simultaneously, get a switch box as Sfar suggested. If you do want to play them all at once, I think that the best approach would be to purchase a separate power amplifier, drive it from the pre-out (not tape out) connections of the Creek, and either use it to power the 4 ohm speaker while using the Creek to power the two 8 ohm speakers in parallel, or vice versa.
Some comments on other possible connection arrangements: Series connection of the 4 ohm speaker with either or both of the 8 ohm speakers would resolve the impedance problem, but would probably affect sonics adversely (series connection of dissimilar speakers will result in compromised sonics, unless their impedance vs. frequency characteristics happen to be similar). Series connection of the 8 ohm speakers with each other, with the 4 ohm speaker in parallel with that combination, MIGHT work in a semi-reasonable manner, but would probably be marginal in terms of both the overall impedance (nominally 3.2 ohms) and the volume level that could be attained on the series-connected 8 ohm speakers.
Regards,
-- Al