You may want to check Edu Falaschi (ex-Angra) project called Almah .
Their second album, Fragile Equality, has frequent parts of symphonic/orchestration keyboards with complex guitars riffs and progressive parts.
I also recommend you to check the Swedish Operatic Metal band Therion , most of their albums have complex orchestrations parts mixed with Power/Melodic Metal.
A very good way to find new bands is searching on related bands from your favourite artists on Last.fm. Or even searching on YouTube for "symphonic progressive metal bands megamix", will return a plenty of good suggestions!
musicfans.stackexchange.com/users/677/Bruno Monteiro
I'd suggest Haggard as a full symphonic band, with "Eppur si muove".
Septicflesh are using a lot of orchestra parts, you can try Titan, Communion and The Great Mass. Dark Lunacy had a violin in Forget me Not and Devoid.
Fleshgod Apocalypse uses piano and various orchestration parts, I'd suggest listening to their Agony album.
Probably less symphonic than previous bands
you can give a chance to old Novembre albums:
Arte Novecento, Classica and Novembrine Waltz.
Their composition is unique, grasps a wide range of sounds, you'd probably like it.
musicfans.stackexchange.com/users/683/Joshi Spawnbrød
When it comes to technical guitars one should definitely mention
Rhapsody(now renamed to Rhapsody of Fire).
Give Gargoyles, Angels Of Darkness a try.
In their older albums Luca Turilli was playing the guitars and he is very talented guitar player.
The band split in 2011 and now there are two bands - Rhapsody of Fire and Luca Turilli's Rhapsody.
You may also give Gwyllion a try (e.g. The Night Awakes ).
It is worth to also mention Morten Veland - some of the peaces of Sirenia and his band Mortemia could also fit in what I imagine as technical guitars.
As for Nightwish I really like the band
and I think some peaces(from the older era) could fit as well - for instance give their interpretation of Crimson Tide And Deep Blue Sea a try.
Of course we can not leave out Therion and Haggard, but they have already been mentioned.
musicfans.stackexchange.com/users/4590/Ivaylo Strandjev
I think you should check the one-man-band (from Behold the Arctopus) project Direwolf:
http://www.metal-archives.com/bands/Direwolf/91376 Fist in Fetus are also technical and symphonic.
Therion, Nightwish, are symphonic, not so technical.
Same thing with Haggard, Septic Flesh and Fleshgod Apocalypse, they are trully symphonic and progressive, but I wouldn't call them technical.
Dream Theater, Pain of Salvation, Dark Lunacy and Novembre don't fit the "Symphonic&Technical" combo either...
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I would also add: Adagio Yngwie Malmsteen
Blind Guardian Therion Evergrey
Uli Jon Roth Also David Maxim Micic's solo albums have a symphonic vibe in them although he does not belong in that genre.
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Direct Answer to Your Question:-- Try "A Glimpse Beyond" by Dan Mumm. ( https://www.youtube.com/watch?v=YnIQnlxhYys )
[ Warning :
Harsh, Noisy, and/or Disorienting Sound in the video link directly above.]
Other References:--
This artist has the advantage of being a professional guitar teacher with materials you can visit:-- ( http://www.danmumm.com/do-you-really-need-theory-as-a-guitarist/ ) ( https://metalmethod.com/sweep-picking-secrets )
musicfans.stackexchange.com/users/5380/Tautological Revelations
When it comes to symphonic metal bands, the guitar parts aren’t usually very complex.  I know two bands which have both symphonic instruments and very technical guitars:   Symphony X   Angra   Failed to find any more. Do you know any?
Symphonic metal bands with very technical guitar
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<similar-artists><metal><symphonic-metal>
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Bands that could be considered symphonic include Haggard with "Eppur si muove", Rhapsody (now renamed to Rhapsody of Fire), Gargoyles, Angels Of Darkness and Blind Guardian  Therion  Evergrey. The bands Haggard, Rhapsody of Fire,  Gargoyles, Angels of Darkness, Blind Guardian, Therion and Evergrey were reccommended
The bands Haggard, Rhapsody of Fire,  Gargoyles, Angels of Darkness, Blind Guardian, Therion and Evergrey were reccommended