There is no question of meditating on something void or impersonal

Teachings of Lord Caitanya, Preface: […] Lord Caitanya’s teachings are identical to those given by Lord Kapila, the original propounder of sankhya-yoga, the sankhya system of philosophy. This authorized system of yoga recommends meditation on the transcendental form of the Lord. There is no question of meditating on something void or impersonal.

One can meditate on the transcendental form of Lord Vishnu even without practicing involved sitting postures. Such meditation is called perfect samadhi. This perfect samadhi is verified at the end of the Sixth Chapter of Bhagavad-gita where Lord Krishna says: “And of all yogis, he who always abides in Me with great faith, worshiping Me in transcendental loving service, is most intimately united with Me in yoga and is the highest of all.” (Bg. 6.47)

Lord Caitanya instructed the mass of people in the sankhya philosophy of acintya-bhedabheda-tattva, which maintains that the Supreme Lord is simultaneously one with and different from His creation.

Lord Caitanya taught this philosophy through the chanting of the holy name of the Lord. He taught that the holy name of the Lord is the sound incarnation of the Lord and that since the Lord is the absolute whole, there is no difference between His holy name and His transcendental form.

Thus by chanting the holy name of the Lord one can directly associate with the Supreme Lord by sound vibration. As one practices this sound vibration, he passes through three stages of development: the offensive stage, the clearing stage and the transcendental stage.

In the offensive stage one may desire all kinds of material happiness, but in the second stage one becomes clear of all material contamination. When one is situated on the transcendental stage, he attains the most coveted position—the stage of loving God. Lord Caitanya taught that this is the highest stage of perfection for human beings. Full Preface