Impact of phase inversion by preamp


This will be my first post on this forum so I thought I’d pose a question I’ve always wondered about.  I have a Conrad Johnson Premier 18LS preamp that I’ve been extremely happy with since first acquiring it some years ago.  This is a solid state single ended, single stage design that inverts the phase of the input signal at the output.  The manual states that you should reverse the connections to the speakers to account for this.  Obviously this is easily done but I really can’t see how it would really matter as long as things are connected consistently between the left and right channels.  I’d be interested to hear what others have to say on this subject.
ligjo
I have found that when the phase is inverted that bass will sound hollow or will be missing a bit.  Some speakers seem to be more impacted by this than others.  I can definitely hear a difference in mine. 
Thanks for the replies guys!  There are no polarity reversal switches in any of my gear so I need to make the changes at the speaker terminals, making quick AB comparisons difficult.  I suppose when in doubt, follow the manufacturer recommendations which is what I do.  Just curious whether it really matters.
I concur with dweller, the impact is subtle, but noticeable.
You should really try using it.
BTW, there are some recordings with the phase inverted, so if you notice something 'off', just toggle the switch and see if it helps.
Bob 
The importance of maintaining "absolute phase" aka "polarity" in a system is controversial. One reason for that is that many recordings have been engineered with a large multitude of microphones, and have been subjected to extensive electronic post-processing, the result being that different instruments and different vocalists may have different polarities on the same recording.

Whatever difference it might make is most likely to occur on recordings that have been made with a minimal number of microphones (ideally just two or three), and that have been engineered with minimal post-processing. Some relatively small producers of classical recordings tend to be in that category.

Also, in the case of preamps which provide a polarity switch it should be kept in mind that when the position of the switch is changed, in addition to the polarity of the signal being inverted the internal circuit configuration of the preamp is being changed. Which depending on the specific design might in itself have minor but audible sonic consequences, especially in the case of preamps that are not "fully balanced," i.e., that have single-ended internal signal paths.

Regards,
-- Al

I have a phase switch on my preamp. It usually has minimal effect. Apparently, you should switch back and forth and use whichever setting results in the best bass. Good first post!