With regard to one who tries to justify davening at home without a minyan because he claims he can concentrate better…

“That is a mistake…One of the many reasons it is important for men to pray in a synagogue with a minyan-quorum of ten men is that it allows you to participate in the repetition of the Amidah prayer after you finish the silent version and thereby attain an additional level of consciousness through your active involvement in the repetition.  Furthermore, part of the repetition is the kedusha-sanctification prayer, which enables you to draw to yourself a great concentration of holiness.  The kedusha can only be said by a minyan.  The Zohar teaches that even the angels cannot say the kedusha prayer by themselves.  They can only participate together with Israel.  ~ The Light of Ephraim (required reading for men)