It's a matter of opinion, but it must be said that, since the
guitar solo was only invented really in the last ~100 years, all
solos may be referred to as "modern." I suggest looking into
"Machine Gun," by Jimi Hendrix.
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Their are lots of places online where someone can listen to
different electric guitar solos. Some of these places are: Youtube,
Guitar Player and Guitar World.
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Songs that have guitar solos and more.
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Comfortably Numb from The Wall has 2 good sized guitar solos,
and High Hopes from The Division Bells.