There is a popular verse glorifying Śrīla Rūpa Gosvāmī:
śrī-caitanya-mano'bhīṣṭam
sthāpitaṁ yena bhū-tale
svayaṁ rūpaḥ kadā mahyaṁ
dadāti sva-padāntikam
This is a verse that many gauḍīya-vaiṣṇavas sing to honor Śrīla Rūpa Gosvāmī. This verse is usually sung while performing maṅgalācaraṇa.
Recently, a few individuals have been asking me why I sing the third quarter of this verse (svayaṁ rūpah kadā mahyam) slightly differently as — "so'yaṁ rūpaḥ kadā mahyam". I was especially asked this by Sriman Dravida Prabhu during one of the talks that I gave.
The reason for my preference of this reading is simple. This verse originally occurs in the Prema-bhakti-candrikā of Śrī Narottama Dāsa Ṭhākura, and in many of the old editions of this work, the preferred reading is — so'yaṁ rūpaḥ.
There is also a Sanskrit commentary on the Prema-bhakti-candrikā by Śrīla Viśvanātha Cakravartī Ṭhākura, and in the commentary too he has preferred the reading "so'yaṁ rūpaḥ". This is highlighted in "Image 1" attached to this article.
A book named "Sri Caitanya Mahaprabhu" authored by Sri Bhakti Pradip Tirtha Maharaja mentions both the readings. This too is attached to this article as "Image 2".
The meaning of the verse doesn't change much at all in this variant reading. While the phrase "svayaṁ rūpaḥ" means "Rūpa himself", the phrase "so'yaṁ rūpaḥ" means "that very Rūpa". Not much of a difference in meaning.
In this way, both readings have been mentioned by various authoritative sources. My preference is to side with the reading of Śrīla Viśvanātha Cakravartī Ṭhākura, since his copy of the manuscript was closer in time to Śrī Narottama Dāsa Ṭhākura, and hence I sing it as — "so'yaṁ rūpaḥ" instead of "svayaṁ rūpaḥ". Both readings are grammatically correct. 
