iMac 27 inch quickest and cost effective way to add second storage SSD

iMac 27 inch quickest and cost effective way to add second storage SSD keeping the optical drive and primary storage intact, ambient relaxing study music LOFI
Primary Storage HDD - 1 TB
Secondary Storage SSD - 1 TB (configure as startup disk)
NOTE: 2nd controller cable for the 2nd storage cost only $9 as oppose to converting primary drive to SSD, cable can cost up to $45. No performance penalty just faster and cost effective.
Music: UA-cam Audio Library

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