Classical concert clothing

Hi,
There will be a symphonic concert in a smaller city of Kyushu next year I wish to see. Tickets are on the way but I am not sure what to wear, as I will be doing a lot of travelling around the weeks after the concert I cannot bring too much.

I suppose pants and a t shirt might seem inappropriate. And as I will probably be the only or one of few foreigners there, I don't want to stick out too much.

Any suggesions for a male traveller
?

I would recommend for guys neat pants (no denim), at least polo or regular shirt, no tie needed but a jacket.

Regular clothes would be fine. I wear jeans on weekend for Kyushu Symphony Orchestra concert.

KyushuLocal is right. The Japanese in general go to ballets, operas and classical symphony orchestra concerts in jeans and sneakers. If you go dressed to the nines, you'd look weird. I miss those fancy concerts in Europe and America, even though I'm Japanese.

But when I went to Phantom of the Opera in London, I wore short boots that are also comfortable enough for sightseeing, a pair of fancy black pants and a very nice blouse. I took off my ordinary down jacket as I entered the venue.

I usually travel in light sweetshirts, for the packing purpose, like this for instance:
https://ehoodiesformen.files.wordpress.com/2013/01/hoodies-for-men.jpg

Have a spring jacket like this, worked fine during autumn:
http://www.jula.se/globalassets/catalog/productimages/902798.jpg

And some walking shoes like this:
https://artimg.footway.com/01/471/47144-02/front/705/705/47144-02.png

Not sure if it is too casual. Bringing like wedding wear or so and extra shoes would be a hassle...

I usually bring a single shirt like this one just in case, but it does not take up much space:
http://decco.se/image/cache/data/Skjortor%20-%20Blusar/Oxford/450024%2...

The single shirt should work.

I dont remember the exact date but it is somewhere late March, so... I would need a jacket anyway.

I managed fine in late October last year in Nara with just a sweatshirt and a t-shirt but I have no idea about spring.

I read that there will be a kid revenue before the concert, because the concert itself is no-kids zone. Not sure if the kids are to wait outside or if the respective parent will wait or return home though.